The Theology of the Council of Nicaea

Rebecca Lyman

The Council of Nicaea in 325 was a critical theological and institutional watershed between the local and often diverse theologies of one God as Trinity in the second- and third-century Christian communities and the universal or catholic credal statements of the ancient imperial church that developed over the course of the fourth century. For the first time bishops from throughout the Roman Empire gathered, at the request and expense of the Emperor Constantine, to debate and declare their beliefs with an expectation of enforcement and unity – i.e. a council of broader representation and authority with a synodal creed. While the origins of the theological conflict in Alexandria that prompted the gathering at Nicaea remain unclear, the decisions at the council and the extensive debates in the decades afterwards on the nature of God created the theological and exegetical foundations of Nicene trinitarian doctrine. No longer imagined through a hierarchical divinity based on causality or separate spheres of activity, the one divine nature and operation of the Father, Son, and Holy Spirit was the eventual result of the extensive theological and exegetical work of the pro-Nicene theologians. Recent studies have been especially attentive to the development of the theological methodology which underlay the defence and exposition of these foundational doctrines. The declaration and enforcement of Nicene orthodoxy by Emperor Theodosius in 381 marked the end of the formal debate, though dissent and persuasion continued. The history of Nicene theology is therefore institutionally complex as well as theologically foundational.

1 Theologies and communities in ancient Christianity

1.1 Diversity, theology, and the rule of faith before Nicaea

Traditional church histories often contrasted ‘orthodoxy’ with ‘heresy’ to map the vigorous theological conflicts of the first three centuries. However, current studies underline the variety and vitality of early urban Christian communities throughout the Mediterranean that resulted in a spectrum of interpretations and teachings, including the creation of orthodoxy itself (King 2008: 66–84). Christianity was unusual as an ancient religion because it was not necessarily linked to a sacred place or ethnicity, so the first communities flourished as voluntary associations or schools, often in continuity with Judaism, which had an intense focus on texts, interpretation, worship, and practice of life (Vinzent 2016: 103–118). The Greek translation of Hebrew scripture, the Septuagint, was the primary source and authority for early Christian life and reflection, together with the emerging religious literature of the first and second centuries which would form the New Testament. Not surprisingly, debates on the definitions of a scriptural canon, hermeneutics, and apostolic authenticity were widespread as the early communities explored and articulated their beliefs and practices within the traditional polytheistic culture of late antiquity (Young 2008: 849–851). These dispersed communities exchanged letters and treatises, and cautioned each other against writings and teachers thought to be harmful; but only by the third century did bishops begin to gather regularly in synods to censure and discipline opponents (Williams 1989: 11–18). Theological reflection on scripture and practice was therefore an integral part of the life of Christian communities in relation to Judaism, other Christians, and surrounding ancient religions and philosophies.

One of the major theological conflicts among the early communities was defining Christian divinity and life as revealed and practised through the central saving work and teaching of Jesus in the light of the Jewish inheritance of monotheism. In antiquity, the concept of monotheism included a range of concepts, from a single being to a single power with mediating agents, or the first of a hierarchy of gods with lesser degrees of divinity increasingly diminished by being in closer relation to the material world (Novenson 2020: 1–8; DeConick 2020: 263–292). Drawing on Hebrew scriptures, Jews and Christians both confessed the absolute singularity and power of one God as creator (Deut 6:4; 1 Cor 8:6). However, other passages in scripture described mediating aspects of divinity as active agents, such as Wisdom (Sophia) as found in the books of Proverbs (8:22–30) and Wisdom (7:26–27). Christian writers identified Jesus with these aspects as the divine mediator and saviour (John 1:1–5; Col 1:15–20), as well as using a variety of unique titles such as ‘Lord/Anointed’ (Acts 2:36) and ‘Son’, which could indicate both divinity (John 20:31) and secondary status to the Father (John 17:3; Fredriksen 2020: 316–319). Reflecting the diversity both of scripture and of local practices of prayer and liturgy, the New Testament had binitarian formulas (Rom 8:11; 2 Cor 4:14; Eph 1:20; 2 John 1:13) as well as triadic formulas (Matt 28:19, 1 Cor 6:11; Heb 10:29) to describe the persons of Christian divinity as the Father, Son, and Spirit. The early Christian debates concerning the nature and actions of God then contrasted scriptural texts of divine equality between the Father and Son (John 1:1; Matt 11:27; Luke 22:70; John 10:30; John 12:45; Col 2:9: Heb 1:3) with those which seemed to subordinate the Son to the power or being of the Father (Matt 10:18; John 14:28; 17:3).

Several dualistic models of God and salvation within the growing Christian communities sharpened the defence of one good God as omnipotent Father and Creator, over and against conceptions of an alien creator responsible for the limits and errors of the material world, as in Marcion, or a lower evil creator (demiurge) in ‘Gnostic’ authors. Following Philo, a Jewish philosophical author and exegete, some Christian intellectuals drew on Hebrew scripture and contemporary philosophy to describe God the Father as the only and eternal source of existence. Within later Platonic cosmology, philosophers increasingly contrasted the absolute goodness and utter transcendence of God to the lower multiplicity and mutability of the physical world (Ip 2022: 15–47). Divine mediators were therefore necessary as lower and active agents to accomplish the divine purpose in creation and history. As a philosophical Christian teacher in Rome, Justin Martyr outlined an apologetic theology in which the Son was the active Word of the transcendent Father, being the mediating lower god in creation and also revealing the eternal and invisible God through the incarnation:

You must not imagine that the unbegotten God himself came down or went up from any place. For the ineffable Father and Lord of all has no place […] for he existed before the world was made. (Dialogue with Trypho 27.1–2, trans. Behr 2001: 103)

‘Gnostic’ Christians emphasized a descending and multiple cosmology and soteriology of divine mediators based on the attributes of God. Writing against them, Irenaeus, the bishop of Lyons, emphasized both one God, the creator and Father, and one Christ, pre-existent and incarnate:

There is, therefore, as I have pointed out, one God the Father and one Christ Jesus, who is coming throughout the whole economy […] the invisible becoming visible, the incomprehensible becoming comprehensible, the impassible becoming passible […] (Against Heresies 3.16.6, trans. Behr 2001: 127)

The entire sweep of saving action by God the Father through the Son as Word in creation and incarnation – i.e. the economy of salvation – rested on the primacy and power of the transcendent and eternal Father, the revealing and transformative divine presence of the Son, and the continuing active power of the Holy Spirit.

In contrast to this development of Logos/Word theology, other theologians in the third century emphasized the unity of divine nature in Christian monotheism. Labelled as ‘Monarchians’ or ‘Sabellians’ by their opponents, they read the scriptural references to ‘Father’, ‘Son’, and ‘Spirit’ as temporary titles that indicated only sequential actions by the one God (see The Spirit in the Christian Bible; Ip 2022: 69–84). This was a means to defend both the oneness of divine nature and the full divinity of the Son. Critics such as Hippolytus and Tertullian rejected this defence of monotheism as compromising the biblical distinctions of the Godhead revealed in scripture, as well as the properties of divine and transcendent nature. The suffering of Jesus would have to be attributed to the Father (patripassianism), or the suffering of Jesus would be only by appearance (docetic), since divine nature by definition was unable to suffer. Rather than a temporary mode of being within one Godhead, the economy of salvation accomplished through the creation, incarnation, and sanctification revealed three persons as the inner being of the one Christian divinity. Other Christians defended Christian monotheism by describing Jesus as simply a human being infused with the Spirit, rather than the incarnate Word of God (adoptionism). From these early debates and ecclesiastical practices, a simple rule of faith emerged as a brief outline of essential teachings (regula fidei) to affirm God as creator and the Son as divine and saviour. These appeared as both declaratory within theological writings and interrogatory in the context of baptism (Kelly 1972: 50, 284). These regula were not universal in form among the early communities but were linked to the context of initiation or debate with no fixed structure or wording (Kinzig and Vinzent 1999: 540–541). Theologians therefore defended certain principles of theological belief in a single divine being – Father, Son, and Holy Spirit – with exegetical underpinnings, rather than exact or universal terminology.

In the early third century, Origen of Alexandria noted these differing opinions of Christians and set out to explicate one body of apostolic doctrine based on scripture, the rule of faith, and theological deduction, in his highly influential and controversial work, On First Principles. This attempt at a more systematic exploration of scripture and theology set the parameters of much of the later trinitarian debates in the fourth century. Origen placed his theological moves and exegetical choices in the explicit context of other Christian opponents: those (Monarchians) who wished to make little distinction between Father and Son in spite of biblical evidence, and those who had obscured the proper transcendence and simplicity of the Godhead by using materialist images of generation such as emanation (probole) (Ip 2022: 84). Like Irenaeus before him, Origen defined the nature and action of one God through both contemporary philosophical assumptions and the soteriological purposes of creation. Thus, the simplicity and goodness of divine nature is manifest in the primacy of the unbegotten Father, and also in the gracious multiplicity of the titles of the only begotten Son which indicate his salvific mediation to retrieve the fallen creation into unity with God (Ip 2022: 119–153). Origen delineated both unity and distinction through his scriptural metaphors of light, eternal generation, and the Son as the image of the Father in act and will (Ip 2022: 155–187). Whether or not Origen used the term homoousios remains disputed (Edwards 1998: 658–670). For Origen, the scriptural titles and descriptions of the Son as Wisdom, Word, and Image of God proved both a distinct divine identity (hypostasis) as well as his soteriological accommodations and mediation to the fallen creation to reveal the transcendent Father. The Father, Son, and Holy Spirit shared divine nature but were distinguished by causality, and at times through participation, to ensure both shared nature and individuality (Edwards 2002: 47–86; Hengstermann 2022: 348–351). Origen’s theology of image was especially rich in describing the relation of the Father and Son as well as the incarnation: the two natures of Christ exhibited the image of God as Word and also perfected humanity as unchanging in goodness and faithful in virtue.

Several decades later, the bishops of Rome and Alexandria exchanged testy letters on negotiating the proper language of divine nature and activity. The bishop of Alexandria strongly opposed local ‘Sabellians’, who in turn appealed to the Roman bishop for support. Their literary exchange would be used by both sides in the later fourth century debates, as Dionysius of Alexandria described the Son as ‘creature’ to distinguish him from the uncaused Father, affirmed three separate persons (hypostases), and initially rejected homoousios (same nature) in order to avoid a muddled divine unity (Hanson 1988: 72–76; Beatrice 2002: 243–250). As seen in the fragments of a third century Alexandrian writer, Theognostus, the scriptural metaphors of light or image continued to be theologically central to describing the unique generation and identity of the Son in ways which distinguished, but did not diminish or divide, the divine nature (Hanson 1988: 77–78). These early debates on the Christian nature of God provided the conceptual outlines and scriptural texts that shaped the later theological arguments and practices during the controversies concerning Trinity and Christology in the fourth century (Ip 2022: 189–199).

1.2 Conflict in Alexandria

The history of the origins of the Nicene controversy remains challenging to reconstruct because of the destruction of sources, the polemical distortions of opponents, and the complex alliances and interchanges shaped by the new political legitimacy of Christians within the Roman Empire (Ayres 2004b: 1–3). After Constantine defeated his rival Licinius in 324 to become sole ruler, he wished to ensure religious unity for the spiritual and political stability of the empire both through his patronage of the church and by adjudicating personally in several ongoing theological divisions. Contrary to popular accounts, which often portray an emperor as dictating policy at Nicaea, Constantine was rather a forceful facilitator for the episcopal gathering and ultimate unity; and, like later emperors, even as he enforced their decisions he ultimately failed to hold the bishops together if they were divided on what they considered to be fundamentals of theology and salvation. In recent accounts of the fourth-century Nicene controversies, historians have traced through the shifting opinions, diversity of opponents, and bewildering succession of ecclesiastical councils the gradual emergence of a theological ‘culture’ or ‘grammar’ that provided rules of discourse to ensure divine simplicity, the primacy of Christ, and a clarification of theological epistemology in exegesis and reflection (Anatolios 2011: 8–9; Ayres 2004b: 4–5). The debates of the councils forced a conversation among geographically diverse Christian bishops and theologians which gradually produced a more consistent vocabulary to describe and defend the mystery of the doctrine of God.

Ironically, ‘Arianism’, as the shadow side of the Nicene orthodoxy, has often been portrayed as an archetypical heresy, yet the actual doctrinal origins of the original conflict in Alexandria have never been fully settled among historians (Wiles 1996: 1–26; Lyman 2021: 47–52). Not only is the literary evidence of the debate – especially the writings of Arius and his colleagues – very limited, these fragments have been largely preserved, and often distorted, in polemical sources (Gwynn 2007: 169–202). Attempts to link Arius’ teaching on the transcendence of the Father to contemporary philosophy (by Rowan Williams), or a populist exemplarism through a created Son (by Robert Gregg and Dennis Groh), or legacies of problems within Origen’s theology have never fully explained the intensity and bitterness of the early debate which first split the Alexandrian church and then attracted powerful outside episcopal allies on both sides (Löhr 2006a: 524–560). This local debate on the proper nature, origin, and worship of the Son hit a vital nerve as it spread among the Eastern churches, still recovering a decade after the end of the Great Persecution under Diocletian and his successors. Since most of his original teachings were abandoned by his allies after Nicaea, Arius has had less importance in the recent histories of fourth-century Nicene theology. He is seen as a catalyst for a larger debate among Christians on the nature of God, rather than the founder of a coherent movement (Ayres 2004b: 12, note 3). Most recently, Arius and his allies have been interpreted as concerned with defending traditional monotheism as a determinative principle, which may reflect current philosophical or social issues, but equally reflects inherited liturgical and devotional themes (Löhr 2006b: 156–157; Anatolios 2011: 42–52).

From the extant documents concerning the controversy, historians have ordered the sequence and dating of events in Alexandria, and recently proposed the events began around 321/322 (Parvis 2006: 78, 100–101). According to Constantine (one of the nearest contemporary sources), Alexander the bishop of Alexandria initiated the conflict by discussing holy mysteries in public, but all clergy were to blame in allowing this arcane discussion to roil the larger community (Urk 17; Opitz 1935: 32–35; Drake 2021: 118–119). The theological conflict was thus not a literary exchange among ecclesiastical elites but a public urban debate about the origin and nature of the Son, taking place between Alexander and a group of his clergy – including, most notably, Arius, a presbyter. This argument spread among the laity of Alexandria, and eventually separated the diocese into separate communities. According to his critics, Alexander compromised traditional and biblical monotheism by his mischaracterization of the eternal relation and shared nature of the Father and the Son. In response, Alexander portrayed his opponents as little better than adoptionists who denied the divinity of the Son, since they insisted on the Son’s separate and lower nature which had come about through the will of the Father.

After a synod of Egyptian and Libyan bishops condemned Arius and his allies, Arius wrote to Eusebius, the powerful bishop of Nicomedia, invoking a shared connection through the martyred bishop, Lucian of Antioch, and suggesting Alexander’s theology – which he portrayed as a muddled Monarchianism – was not shared by many Eastern bishops (Urk 1; Opitz 1935: 1–3). Several bishops then wrote to Alexander to correct him about the traditional and necessary primacy of the Father, including Eusebius of Caesarea (Urk 7; Opitz 1935: 14–15). Alexander issued two encyclical letters describing the theological and biblical errors and arrogance of his opponents, including separate assemblies, lawsuits, and unruly women (Urk 4, 14; Opitz 1935: 6–11, 19–20). Arius composed an apologetic theological piece, the Thalia, perhaps to clarify his controversial positions for other allies (DelCogliano 2018: 477–492). This continuing public disorder in Alexandria may have led to the edict of Licinius in the Eastern portion of the empire against the meetings of bishops and the instruction of women by men (Barnes 2014: 105).

In a statement of faith, the dissenting clergy accused Alexander of violating traditional monotheism which in scripture and tradition affirmed one God who begat one only begotten Son. They affirmed the bishop’s own leadership and teaching on monotheism, and also noted his opposition to descriptions of sonship based on emanation (Urk 6; Opitz 1935: 12–13; Hanson 1988: 7). Their own defence of the primacy and singularity of the Father relied on their description of the creation of the Son by omnipotent will before time:

He who has begotten the only begotten Son before aeonian times […] giving him existence by his own will, unchangeable and unalterable, a perfect creature (ktisma) of God, but not like one of the creatures, a product (gennema), but not like one the things produced […] not as Valentinus laid down an issue (probole) nor as Mani taught a consubstantial part (meros homoousios) of the Father, nor as Sabellius said, dividing the Monad, a ‘Sonfather’ nor as Hieracas, a light lit from a lamp or a lamp spread in two. (Urk 6.2–5; Opitz 1935: 12–13, translation in Hanson 1988: 7)

The Father did not deprive himself of that which he possesses as unoriginated (agennetos). The Father is defined as ‘supremely sole (monotatos), without beginning, monad, and origin of everything’ (Urk 6.8; Opitz 1935, translation in Hanson 1988: 8). Arius later wrote to Eusebius of Nicomedia,

[t]hat the Son is not unbegotten (agennetos) nor in any way a part (meros_) of the unbegotten nor derived from some substratum, but he exists by will and counsel before time and before ages, full of truth, and grace, God, only begotten […] And before he was begotten or created […] he did not exist. For he is not unbegotten. (Urk 1.2–3; Opitz 1935, translation in Hanson 1988: 6)

In this letter, Arius also stated that the Son derived from non-existence. While Arius and his allies would insist that the Son was ‘begotten’ in a unique relation to the Father, he was necessarily separate in nature as having a beginning, and therefore a different existence or nature (hypostasis) from the uncreated Father. This unique process however also distinguished him from the rest of creation. Only the omnipotent will of the transcendent Father ensured the status of the Son as ‘god’ rather than sharing a common or derivative nature. In comparison to the eternal and uncreated Father, the Son had by definition come into being and so subsisted by the will of the Father. He was unchangeable as a perfect creature and Son by divine will, so he was not equivalent to those created later by divine will through the Son.

In his later work the Thalia, Arius outlined an apophatic theology and spirituality that denied the knowledge or vision of the one transcendent Father to the Son, except as granted to him by divine will:

God himself, in himself, remains mysterious (arretos). He alone has no equal, none like him, none of equal glory. We call him unoriginated in contrast to him who is originated by nature […] we praise him as without beginning in contrast to him who has a beginning, we worship him as eternal in contrast to him who came into existence in times. He who was without beginning made the Son a beginning of all things which are produced, and he made him into a Son for himself, begetting him […] So the Son having not existed attained existence by the Father’s will. He is the only begotten God and he is different from any others. Wisdom became Wisdom by the will of the wise God and so he is apprehended in an uncountable number of aspects (epinoia). He is God’s glory and truth and image and Word […] He is the mighty god (Isaiah 9:15) and in some degree worships the creator. God is mysterious to the Son, for he is to him that which he is, ineffable. (De Synodis 15, translation in Hanson 1988: 14–15)

The biblical designations of the Son (Wisdom, Word) therefore remained proper to the Father as his eternal attributes, so that all the Son had, including these traditional descriptions, was solely given by the Father (Gwynn 2007: 189–220). This apophatic theology defended Christian monotheism, but radically altered the traditional being of the Son as the incarnate revelation of the transcendent Father. The Son’s knowledge of the Father was only by the gift of the Father (Matt 11:27). According to Winrich Löhr, Arius’ apophatic theology ‘[…] implies the abrogation of the intellectualist agenda of much of late antique philosophy – both pagan and Christian […]. The emphasis is on praising and glorifying […] divine transcendence is democratized’ (Löhr 2006b: 149). The revelation of God appears to be only through relation and action modelled by the Son (Heb 2:8–18).

The teachings of Alexander exist in two letters which he composed to neighbouring bishops to justify his opposition and discipline of Arius and the other clergy. These letters offer further controversial clues about the teaching of his opponents. Alexander claimed that they mistakenly and myopically focused on the texts of the Son’s humility and suffering (Phil 2:8) in order to separate him from the Father. They claimed that only the foreseen virtue of Christ led to his sonship (Ps 45:7), and so all believers could also become sons of God (Heb 1:9). Alexander thus argued that their theology ignored the clear biblical testimonies to the divinity of the Son: he could not be ‘created’ because all things were created through him as the Word (John 1:1–3). Things created were nothing like ‘the one who is’ (Exod 3:14); the Son was not like creatures nor an adopted son, but his likeness to the Father is precisely what reveals the Father (John 14:8–9). Alexander admitted that only the Father is unbegotten and therefore generation is a mystery, but the Son as essential Wisdom and Word has always been with the Father (Urk 14.27–29; Opitz 1935: 23–25). Although his ‘uneducated’ opponents insisted that there must be either creation from nothing or two unbegottens, Alexander maintained that scripture revealed the unique glory of the unbegotten Father and the Saviour who acknowledged that the Father is greater than he (John 14:28; Urk 14.44, 52; Opitz 1935: 26, 27–28). Recent studies have noted the innovations of Alexander in his formulation of eternal generation and his understanding of the Son as eternal image (Ayres 2004b: 43–52). While Origen had affirmed eternal generation as a means of ensuring the immutability of God than the equality of the Son, Alexander in his two extant letters underlined the eternity of the Son as Wisdom and Word to affirm a single incorporeal and shared divine nature. For Alexander, the Son was thus worshipped with the Father, and revealed the Father as his likeness and image (Hanson 1988: 140–145).

Both sides in Alexandria were on new theological ground in their passionate defences of monotheism in Christian divinity. For the dissenting clergy, Alexander had ignored the traditional and biblical definitions of the Father as the sole and eternal cause of all. For Alexander, his opponents’ insistence on the origin of the Son by will, in spite of their explication of ‘only begotten’ as unique, made the Son only a creature. For the first time, both sides consistently distinguished divinity and created being through the doctrine of ‘creation from nothing’ (creatio ex nihilo). In past theological debates, scriptural references to begetting (Ps 2:7) or creating (Prov 8:22) had been used interchangeably to describe the Son’s derivative and divine nature. This new sharp cosmological divide between the unchanging and eternal creator and the contingent and mutable creation left the former mediating and hierarchical scriptural definitions of the Son as Word or Logos or Image ontologically ambiguous: how can eternal divine nature by definition be compound or shared? Does a language of begetting mean both share unbegotten nature?

The sharp emphasis in Alexandria on the problem of two co-eternals and the singular power of divine will may be due to the presence of Manichees in Egypt, who taught two divine co-existent principles (as noted by the dissenting clergy in their letter to Alexander), or the criticism of Origen’s doctrine of eternal creation by Methodius which emphasized the omnipotent will of God (Edwards 2015: 137–142; Lyman 2021: 50–51). The earlier and intense persecution by Diocletian had also included a propaganda war by polytheists against Christian theology. Christians, it was claimed, were not monotheists because they worshipped a man (Shin 2018: 18–25). For Alexander, the scriptural references of Wisdom or Image proved the Son’s eternal and divine nature in that he was proper to the Father, which in turn guaranteed the authority of his revelation and confirmed the practice of worship of the Son. For his opponents, these scriptural references are only titles given to the Son by the undivided Father, who still possessed Wisdom or Word as proper to himself in the radical simplicity of divine nature. For Alexander’s opponents, the Son remained as the unique revelator of the Father, but solely by the Father’s gift, unchanging by the will of the Father yet also linked to humans as the first born of every creature, and perhaps an exemplar of faithful virtue (Col 1:15–18; Rom 8:29).

Theological models of incarnation and revelation differed considerably among theologians in the early fourth century, even among the alliances of bishops that emerged during the spreading controversy. The earlier mediating – often secondary – status and language about the one Son in creation and incarnation was now awkwardly placed over the new cosmology of creatio ex nihilo. Alexander argued that only an eternal Son could reveal the transcendent Father as his image (Heb 1:3), and he is worshipped together with the Father. The dissenting clergy affirmed a pre-mundane begetting or creation of the only Son, yet the Son acknowledges the Father as God (Mark 10:18) and, according to Alexander’s polemical account, he was the first of many brothers (Heb 1:6) who all advance to the knowledge of God (Gwynn 2007: 187–220). In contrast to Alexander, Marcellus of Ancyra, an opponent of Arius, reserved the title ‘image’ for the incarnate Christ, who was physically visible, and therefore this title could not be used of the pre-existent Word. Eustathius of Antioch criticized the ‘Arians’ for having no doctrine of a human soul in the incarnation, so that all incarnate experience had to be attributed to the separate and created Logos in order to protect the integrity of the transcendent and impassible Father (Parvis 2006: 54–60). Years later, Athanasius would portray Alexander’s opponents in the streets of Alexandria asking impertinent questions of women and young boys: are there two co-existent principles? Is he made of wood or stone, or can he change? Did you have a son before you had a son? (Lyman 2021: 59 note 83). These varied opinions among bishops and on the streets give insight into the intensity of the Christian defence of one transcendent being and the complexity of scriptural language to be reconciled concerning divine and human natures. Athanasius would later apply a ‘double account’ of exegesis to distinguish which texts were applied to Christ’s divinity or to his humanity: Christ is unchangeable as divine and changeable as human (Gwynn 2012: 76).

In 324/325 a synod at Antioch – probably assembled by Ossius of Cordova at Constantine’s request to settle a dispute about episcopal succession – added a synodal confession to address the issues of the ongoing theological turmoil in the Eastern part of the empire. Avoiding definitions of a common nature, the Son was affirmed as simply ‘from the Father’. ‘Image’ was a central definition to defend the Son as eternal, therefore not mutable, and the Son was explicitly defined as begotten and not created. They also condemned a number of positions concerning his ‘creation’ or ‘changeability’. In addition, several bishops were condemned for their theologies, including Eusebius of Caesarea (Urk 18; 1935: 36–41; Parvis 2006: 77–81).

2 The council of Nicaea: theology, scripture, and creed

2.1 Theological formulations and episcopal unity

With no extant Acts describing the proceedings of the council, the sources for the events at Nicaea are very limited and indeed conflicting. They draw primarily from Eusebius of Caesarea, Athanasius, and Eustathius of Antioch, as well as later inventions by church historians. This has resulted in historical ‘calculated guesswork’ to construct a history of the proceedings (Gwynn 2021: 90–91). The original gathering had been set for Ancyra, but Constantine, possibly under the influence of Eusebius of Nicomedia, changed the site of the council to Nicaea, a wealthy city on Lake Askania in northern Bithynia. Nicaea was easier to reach from Italy, closer to Nicomedia (which was the site of the imperial palace), and did not have a bishop of rank who was associated with a particular side of the conflict, whereas the bishop Marcellus of Ancyra was an open and powerful supporter of Alexander (Jacobs 2021: 69–75). The emperor covered all the costs of the transportation of bishops, each with two priests and deacons attending him. There was no sizeable Christian population or church in Nicaea, so the assembly probably met in a large private residence or palace (Jacobs 2021: 78–79).

Like many aspects of the council, the number of the attending bishops is a combination of legend and scriptural numerology; the traditional number was 318, modelled after the servants of Abraham (Gen 14:14). The more likely estimate was around 200–250 bishops plus their retinues, predominately from the East. The total number could have been 2,000, including attendees such as Athanasius as a deacon (who attended with Alexander, his bishop, but did not sign the creed and probably did not speak at the proceedings) and the imperial officials, such as Philumenus, who supervised the signing of the creed (Gwynn 2021: 92–95). Ossius of Cordova, who was the first signer of the creed, was probably the presider; he was followed by the two presbyters who signed on behalf of the Roman bishop.

As Everett Ferguson observed, councils were not yet institutions but events: participants came to gather, discuss, clarify, and (for some) to win (Ferguson 2008: 438). The volatility of participants in ancient church councils reflected the usual process of decision in Roman culture. Even with the absolute power of the emperor or colonial administration, participants at events could influence policy through acclamation or argument, though the decision ultimately had to be endorsed (or coerced) as a majority and final decision (MacMullen 2006: 20–21). Later councils involved a variety of theological advisors, lay and ordained, as well as clerical assistants around the voting bishops, but little contemporary evidence exists for this at Nicaea. Constantine joined the bishops for the opening of the council in late May or early June and, according to Eusebius, graciously sat on the same level with them, and urged harmony; a later legend portrayed him as burning the diverse theological petitions given to him to illustrate the point of necessary unity (Gwynn 2021: 99). The heavy-hitting urban episcopal protagonists of the earlier conflict had arrived at Nicaea interested in the vindication of their own theologies, as well as sorting out structures of authority whose vagueness had limited their jurisdiction and invited unwelcome external theological intervention. Eusebius of Caesarea in particular was interested in rehabilitation after his condemnation at the recent Council of Antioch. Scholars now believe Eusebius of Nicomedia gave the opening speech of welcome as the local metropolitan (Gwynn 2021: 97).

After weeks of negotiation, the council succeeded in producing a common theological statement to bring unity – or at least stabilize conflict – among the bishops. Only two Libyan bishops, Secundus of Ptolemais and Theonas of Marmarica, refused to sign the creed. Eusebius of Nicomedia and Theognis of Nicaea later claimed that they did not accept the anathemas because they did not reflect the true teaching of Arius, who was condemned and exiled. According to a later letter, the council also addressed the date of Easter. Following the customs of Rome and Alexandria, all Christian churches would celebrate on the same day, and not follow the Jewish dating of Passover (McCarthy 2021: 188–191). Eusebius preserved Constantine’s letter, which promoted this unity as well as a condemnation of the Jews. He also related that the churches of Syria and Mesopotamia were the only ones who had to change their traditions, and not altogether willingly (Gwynn 2021: 103).

In Egypt, another division had roiled the Christian community, over the legitimacy of leaders who had absented themselves from their communities during the earlier persecution. This ‘Melitian’ schism had resulted in parallel ecclesiastical structures in Egypt, but the council affirmed that their clergy could remain in place, if secondary to the clergy of Alexander. Later, church historians added dramatic confrontations at the council by scarred confessors and uneducated ascetics defeating learned philosophers in order to demonstrate the Christian power of simplicity and the imperial desire for peace and unity (Lim 1995: 182–216; Gwynn 2021: 106–107). According to Eusebius, the bishops concluded the event by joining the emperor at a feast on 25 July to celebrate his Vicennalia (twenty years of rule) at his palace in Nicomedia (Gwynn 2021: 108).

2.2 The synodal creed of 325

We believe in one God, the Father Almighty, Maker of all things both visible and invisible; and in one Lord Jesus Christ, the Son of God, begotten from the Father, only begotten, that Is from the substance of the Father; God from God, Light from Light, true God from true God, begotten, not made, consubstantial with the Father; ‘through whom all things came into being’ (John 1.3; 1 Cor 8:6), both things in heaven and things on earth; who for us humans and for our salvation descended, became incarnate, was made human, suffered, on the third day rose again, ascended into the heavens, will come ‘to judge the living and the dead’ (2 Tim 4.1; 1 Pet 4:5); and in the Holy Spirit. The catholic and apostolic Church anathematizes those who say, ‘There was when he was not’, and, ‘He was not before he was begotten’, and that he came to be from nothing, or those who claim that the Son of God is from another hypostasis or substance (or created) or alterable, or mutable. (Edwards 2021: 156)

As a product of an imperial and ecumenical council, this ‘synodal creed’ was a new type of statement of faith which had a broad geographical application and also ecclesiastical power (Ferguson 2008: 428–429). Declaratory creeds as forms of pledges to a specific set of doctrinal statements only began to appear in the fourth century amid the broadening theological crisis between Alexander and his opponents (Kinzig and Vinzent 1999: 552). These statements included building blocks of ‘anti-logic’ (statements to correct and exclude opponents) and ‘tradition’, i.e. language of scripture and inherited theology (Kinzig and Vinzent 1999: 555). The synodal creed was a document created and shared only by bishops, who could then be expected to enforce its contents at home. The exact origins of the Nicene Creed remain part of the historical puzzle of the largely undocumented events of the council, but the resulting patchwork of traditional and scriptural language can suggest the significant issues of concern and the necessary compromises.

The crucial theological debate lasted over several weeks, but the actual events remain difficult to reconstruct or synthesize (Gwynn 2021: 97–102; Parvis 2006: 85–91). A key piece of evidence is an explanatory letter by Eusebius of Caesarea written to his own diocese immediately after the council. His presentation of his local creed to the council may have happened early in the proceedings in order to seat him as an orthodox participant (Gwynn 2021: 99; Johnson 2021: 208–222). As Aaron Johnson noted, Eusebius’ sense of hope in an imperially unified church pervades his description of all participants actively debating theological language, even as he himself ‘resisted even to the last minute’ certain statements to demonstrate the serious intellectual acumen and care for tradition at the council (Johnson 2021: 211, 221). By contrast, Eustathius of Antioch asserted that a document which revealed the blasphemy of Eusebius was torn up, and silence was imposed for the sake of order; this could be a document by Eusebius of Nicomedia opposing any use of homoousios (Gwynn 2021: 99). In sharing a common name with the bishop of Nicomedia, Eusebius of Caesarea might have wished to communicate immediately after the council about the favourable reception of his own document.

The final extant account was written much later by Athanasius in the midst of a defence of the term homoousios. He dramatically contrasted two sides of orthodox participants and ‘Eusebians’ struggling, and failing, to define a common theology in purely scriptural terms, that is, in terms of ‘power’ or ‘image’; the heretical participants accepted the biblical terms with duplicitous winks and whispers in the hopes that these could be parsed to their own erroneous ends (Gwynn 2012: 87–89). However, as revealed in the complex debates after the council, the geographically diverse bishops in attendance could hardly be reduced to simply two sides. The theological compromises of the final language of the creed in fact reveal a careful construction of phrases to preserve traditional and scriptural language as well as exclude the defenders of Arius and his colleagues.

In the letter to his diocese, Eusebius of Caesarea claimed that he presented their local baptismal creed to the council. This creed affirmed the ‘Word’ as God from God, Light from Light, only begotten Son, first born of creation, begotten from the Father before all ages. He asserted that Constantine approved this statement, and would have simply added ‘homoousios’ to it, but another statement was drawn up. As noted by Mark Edwards, this creed from Caesarea indicates two fourth century additions to other extant statements of faith by including ‘Word/Logos’ as the title of the Son as well as ‘only-begotten’ (Edwards 2021: 143–144). These were biblical terms under intense discussion in the original controversy in Alexandria. The final creed of Nicaea highlighted ‘Son’ rather than ‘Word’ and used ‘only begotten’ to highlight the meaning of the singularity of divine begetting. This was instead of ‘first born’, which had connotations of order (Col 1:15) with other creatures, including humans (Rom 8:29; Col 1:18; Rev 1:5), and was omitted from the final creed.

In the Nicene Creed, sonship and the understanding of ‘begotten’ in contrast to ‘created’ was carefully outlined to signal and ensure the divinity of the Son. The Son was thus begotten ‘from the substance of the Father’, which assured divinity not explicitly found in the common proof text ‘today I have begotten you’ (Ps 2:7). Another innovation was to include ‘true God from true God’ together with ‘Light from Light’ to show no diminishment of divine nature (1 John 5:20; Edwards 2021: 145). Notably, there is no reference to time or eternity in the creed, which had roiled the original controversy over monotheism in Alexandria, though it is addressed in the anathemas; ‘before all worlds’ would appear in the later version of Constantinople (see God and Philosophy of Time; Kelly 1972: 303; Radde-Gallwitz 2023: 228–231).

A controversial part of the creed was the use of substance language in relation to the divine nature of the Father and the Son (Edwards 2021: 145–149; Hanson 1988: 181–202). In addition to the affirmation that the only begotten Son was from the ousia of the Father, the term homoousios (same substance) was the concluding term which underlined the council’s understanding of ‘begotten, not made’. For many, this word had negative heretical and material associations, including the shared spiritual nature in ‘gnosticism’ and Manicheanism. Dionysius of Alexandria had rejected it as ‘Sabellian’ and, as would be later discussed by Athanasius, it had been denounced at the Council of Antioch in 268 against Paul of Samasota (Hanson 1988: 192–194; Beatrice 2002: 243–272). In the creed, the non-scriptural word concluded and summarized the definitions of divine begetting before the narration turned to the creation and incarnation. Though controversial, the term by design short-circuited any interpretation of the Son as a creature, since it had been explicitly rejected by opponents of Alexander (Hanson 1988: 197; Ayres 2004b: 90). Eusebius claimed that Constantine suggested the term, though other sources credit Alexander, who introduced it precisely to exclude Eusebius of Nicomedia and his other opponents (Edwards 2021: 148–149). Whatever the origin, the term decisively shifted divine causality away from categories of will or time towards divine nature which the begotten Son received from the Father. Later confusion, however, would result from the anathema against those who say ‘the Son of God is of another hypostasis or ousia’; although these terms were seen as synonymous by some, others could read this as a careless or even ‘Sabellian’ lack of distinction as persons between the Father and the Son (Hanson 1988: 167–168). The other phrases condemned were ‘there was a time when he was not’; ‘[h]e was not before he was begotten’; and ‘that he came to be from nothing’ or ‘alterable’ or ‘changeable’ which would define him as a creature (Edwards 2021: 145). Edwards also accepts that a final anathema condemned the use of ‘made’ of the Son, which appears in an account by Philostorgius, a non-Nicene historian (Edwards 2021: 151).

Eusebius’ discussion of the Nicene Creed in his letter also offered a glimpse of the continuing reservations around these key phrases which would persist in the debates in the following decades. His objections to the phrases ‘from the substance of the Father’ or homoousios have to do with the traditional fear of materiality or division in divine transcendent nature, so he claimed that the Son was indeed from the Father, but not a part. ‘Begotten’ with regard to divine nature could only mean that the Son was of a nature too high for creation and ineffable; no division or change occurred in the Father’s unbegotten nature, and the Son is not another hypostasis or ousia, but from the Father (Hanson 1988: 165–166). Defending the primacy of the Father as well as ensuring the divinity of the Son remained essential for him. He also supported the imperial authority of the creed in his portrayal of Constantine as the theological expert who provided reconciling readings of the controversial phrases. Athanasius would later draw on Eusebius’ explanation, which perhaps reflected an imperial interpretation, in order to persuade reluctant churchman of a limited sense of homoousios (Ayres 2004a: 358–340).

2.2.1 Canons

The work of the council also addressed a range of disciplinary problems with regard to clergy, as well as lingering problems from the recent persecution against Christians by Licinius. Critical issues of jurisdiction and mobility underlay the theological conflict which spread so rapidly from Alexandria into the larger Eastern church. Resembling in form imperial citations and Roman law, there are few extant canon collections from this period and area of Christianity: Ancyra 314; Neocaesarea 315; and Antioch 330 (Weckwerth 2021: 158–160). The majority of the twenty canons addressed clergy behaviour. The first three limit radical charismatic practices: self-castration was prohibited, and clergy were not permitted to live with ascetic women who were not members of their family. The second was to prohibit immediate ordination to priesthood or episcopacy of recent converts (1 Tim 3:6–7). The next cluster clarified episcopal succession and power: bishops could only be appointed with the consent of three bishops and the metropolitan. If a bishop excommunicated a priest, it was not permitted for him to be received by another bishop; however, twice a year the bishops would meet to review these disciplinary actions. In the next canons, the ecclesiastical jurisdiction was aligned with the provinces established by Diocletian and Constantine (Weckwerth 2021: 164). The jurisdiction of metropolitans over other local bishops was then defined: the Bishop of Alexandria was defined as including Egypt, Libya, and Pentapolis. The jurisdictions of Antioch and Jerusalem were also clarified.

The next sequence of canons (8–14) addressed the continuing chaos in Christian communities in the face of political and religious attack. They established consistency in the requirements of ordination and also in the penance and restoration of those who had lapsed (sacrificed) under recent religious restrictions by Licinius (Barnes 2014: 105–106). The clerical orders of anyone who had been ordained quickly with no proper vetting were now null and void. If one was ordained and lapsed he was deposed. Those who had lapsed during the rule of the Roman Emperor Licinius could be admitted after twelve years of penance.

The final section strengthened episcopal power and orthodoxy by regulating the behaviour of clergy: specifically, forbidding clergy to move from city to city and bishops from receiving wandering clergy (canons 15–16). Clergy were not to practise usury. Deacons were to receive communion after presbyters and did not sit with them. The followers of Paul of Samasota were deemed heretics, who needed to be rebaptized and re-ordained in order to be received in the church. Deaconesses, however, were not clergy, since no hands had been laid upon them; this might imply a plurality of practice with regard to the status of deaconesses. Finally, this section instructed that Christians should not kneel for prayer on Easter or Pentecost.

3 Toward a trinitarian theology in the fourth century

In spite of the novel glamour of an imperial council and the hard-fought statement of unity, the theological conflicts which prompted the meeting at Nicaea continued especially in Eastern Christian communities. The theological consensus of the quarrelling bishops began to unravel almost immediately. As shrewdly observed by Sara Parvis, the initial reception of the Council of Nicaea was a concerted effort to replace it, by repeating the process of an imperial and ecumenical council (Parvis 2021: 226). In 327, Arius was recalled from exile but was unable to return to Alexandria, and eventually died in 335 just before being received back into the church. Eusebius of Nicomedia was reinstated in his diocese and eventually became bishop of Constantinople; he sent out missionaries to Armenia, India, and perhaps the Goths, though his opponents tarnished his continued influence as ‘Eusebian’ (Hanson 1988: 28–29). Athanasius would be elected bishop of Alexandria, but would later be deposed and exiled to the West in 335; Marcellus would join him in 336.

While traditional histories traced the dualling theologies of ‘Arians’ or ‘Eusebians’ against the defenders of Nicaea over the next five decades of the fourth century, these binary and polemical categories were largely created by Athanasius during his exile in Rome with Marcellus in 340 (Parvis 2006: 180–192). In fact, beneath this ecclesiastical and political search for a unifying statement over the next decades, there was intensely creative theological work. The struggles of the theologians and bishops revealed the continuing geographical and theological diversity of Christian communities and the breadth of interpretation within the inherited apostolic tradition. Defenders, opponents, and those simply uneasy with the language of Nicaea held much in common, including a preference for scriptural language, yet exegesis by itself increasingly convinced no one (Vaggione 2000: 85–86). Until 350, the controversial term homoousios would rarely appear. The famous semantic confusions concerning ousia and hypostasis or distinguishing ‘begetting’ and ‘creating’ by one letter in Greek simply illustrate the problems of the diverse scriptural and theological inheritances of the local Christian communities (Hanson 1988: 181–207). Over two generations a shift gradually emerged in the Christian imagination toward a trinitarian doctrine of one God as Father, Son, and Holy Spirit that embodied not only both words but also the soteriological scope of scripture, the practices of tradition including prayer, and the larger and ordinary experience of the communities (Vaggione 2000: 103–105). These shifts rested on the creation of consistent and shared exegetical and theological practices, a ‘grammar of theology’ that in affirming divine simplicity regulated the problematic and conflicting inheritances concerning singularity, hierarchy, and causality within the Godhead (Ayres 2004b: 14, 273–301; Anatolios 2011: 1–11).

In the immediate aftermath of Nicaea, certain theologians defined Christian divinity through one eternal and shared nature (one hypostasis or ousia) of the Father and the Son which ensured authentic revelation and divinization in the incarnation, while others felt equally strongly that traditional monotheism must maintain distinctions (three hypostases), so that the unbegotten Father remained the transcendent source of all and the Son was the agent and visible subject of all earthly experiences (Lienhard 1987: 415–437). The first alliance included Athanasius, Marcellus, and Eustathius who, although diverse in their own theologies, saw their opponents as essentially polytheistic in their defence of three hypostases, and probably adoptionist, since the Son did not share the divine nature with the Father. The second alliance of Eusebius of Caesarea and Eusebius of Nicomedia saw the first as bordering on ‘Sabellianism’ and ignoring the clear biblical hierarchy and divisions of the divine activity of the Father and Son. This unity would result in patripassianism, if not doceticism, as the Father ‘suffered’ or the suffering of the divine Son was denied (Parvis 2006: 39–68).

These oppositions surfaced in the ecclesiastical conflicts among these bishops well as in literary theological battles. Creating a new version of non-Nicene theology, Asterius the Sophist defended Eusebius of Nicomedia by describing the Son as the image of the Father’s ousia and will, hoping to delineate distinction in unity (DelCogliano 2006: 458–460; Parvis 2021: 234–235). By contrast, Marcellus of Ancyra had a dynamic understanding of the one Godhead (one hypostasis) from which the Logos became ‘Son’ and ‘Image’ only at the incarnation. God as monad became triad, but this was restored again to unity at the final judgment when God became all in all (1 Cor 15:24–8). He attacked Asterius’ definition precisely because the language of ‘image’ by definition implies a separation of being and identity; Col 1:15 (‘image of the invisible God’) must refer to the incarnation (Parvis 2021: 235–237). Eusebius of Caesarea wrote against Marcellus, who was eventually excommunicated in the East but was received as orthodox in the West based on his confession of faith (Parvis 2006: 129–132).

Over the next twenty years, a series of councils would reveal the variety of theologies which sought to avoid or replace the allegedly materialist implications of homoousios. In 341, the Council of Antioch under Eusebius of Caesarea’s episcopal successor Acacius was hosted by the new emperor Constantius to dedicate a church which had been founded by his father ten years earlier. Like his father, Constantius pushed his bishops in the East to find a theological compromise that would settle their disputes and provide a unified piety for a peaceful empire. Earlier in 341, Pope Julius had re-admitted Athanasius and Marcellus to communion, as well as defended Nicaea, so the Eastern bishops wished to justify their earlier decisions in response to the Western statements. Protesting that they were not ‘Arian’, they composed the ‘Second Creed of Antioch’ or ‘Dedication Creed’ (Kelly 1972: 264–274). This statement affirmed the many scriptural names of the Son (Light, Way, Truth) and his eternity, refuting ‘Arian’ formulas, but also defending the divine nature as ‘three in subsistence’ (hypostasis).

In the East, Acacius and Basil of Ancyra represented the new theological consensus in contrast to the West (Parvis 2021: 241–242). In 358, Basil of Ancyra at Sirmium proposed a formula of ‘like in substance’ to describe the relation of the Father and the Son, partly to oppose more radical thinkers like Aetius. However, in 359, another council in Sirmium produced the ‘Dated Creed’ which removed any reference to ousia: ‘Since the term […] was adopted by the fathers rather naively, and not being known by the people causes scandal because the Scriptures do not contain it […]’ (Parvis 2021: 250). A majority of bishops at the Council of Ariminum in the West apparently initially rejected this creed in favour of Nicaea. Later compromises in a search for unity resulted in a rejection of the controversial ousia categories and an affirmation of the dissimilarity of the Father and the Son, which prompted increasing controversy in the West at this theological distance from Nicaea (Williams 2021: 310–323). The Council of Seleucia preferred the Dedication Creed, but in 360 Constantius – through the Council of Constantinople – banned Nicaea and the Dedication Creed by rejecting all ousia language (Parvis 2021: 251). Having managed to offend all sides of the dispute, and especially many bishops in the traditionalist middle, Constantius died the following year. In 361, Julian, a former Christian who intended to revive traditional polytheism, refused to support any side in the conflict and, after he became emperor, Julian recalled all ecclesiastical exiles.

A formidable theological challenge to Nicaea had appeared in the teachings of Aetius and his pupil Eunomius, sometimes called ‘Neo-Arians’ (Hanson 1988: 598–638). They opposed Nicaea by analysing the unique nature and power of God as creator. Defining divine nature as essentially ‘unbegotten/agennetos’, Aetius taught that by definition it could not be shared. Divinity must be ‘heterousian’ (differing in substance) in order to protect the singularity of the Father and the separate reality and agency of the Son. Contrary to Arius’ earlier apophatic theology, this essential definition of divine nature made God comprehensible; knowing the name of God was essential to Christian hope, and Eunomius criticized his opponents for perverting or obscuring what was clear in divine revelation by using appeals to divine mystery (Vaggione 2000: 254–265). Eunomius defined the Father alone as unbegotten, and the Son and Word therefore as begotten as divine, but also the mediator who could change and thus be incarnate to reveal and accomplish salvation. If the Nicenes condemned their opponents for the humiliation of the divine Word with their emphasis on his obedience and suffering to prove his distinct nature, the non-Nicenes retorted that a theology of incarnation of divine nature seemed to erase the biblical reality of the experiences of the suffering Son (Vaggione 2000: 113; Gavrilyuk 2006: 101–134). As in the earlier debate in Alexandria, problems of incarnation were inevitably woven into defining the distinctions and saving actions of the Christian Godhead.

Beyond these imperial councils and duelling theological treatises, Eastern and Western cities contained diverse communities of Christians of opposing theologies which would persist into the next century (Williams 2021: 318–323). Some bishops mumbled at critical moments in the liturgy in order to remain unaligned, barbers offered opinions on the origins of the Son, and some such as Athanasius were valorised for their heroic and lifelong theological commitments. In the newly expanding ascetic movement, some monks avoided controversy while others like Anthony supported Nicaea; the virgins of Alexandria were divided by doctrine (Brakke 1995: 57–79). Intellectuals such as Origen had always grumbled about the varied levels of comprehension in the congregations, but the problem of a newly-legitimate and heavily financially-endowed church embroiled in endless public discussions led others to argue that theology should now be reserved to experts in order to safeguard popular belief (Vaggione 2000: 100–102; Lim 1995: 109–148). As seen in the mid-century urban turmoil surrounding Athanasius and non-Nicene bishops in Alexandria, public civic order and religious life were increasingly intertwined (Haas 1997: 273–277). The Apostolic Constitution provide evidence of a liturgy perhaps used by followers of Eunomius, but this appears simply to attach instruction and devotional admonishment about the ‘only unbegotten God’ to traditional rituals (Vaggione 2000: 258–261). However, in this age of establishment and division, private worship became more suspect and prohibited for fear of error (Bowes 2008: 191–202). Gradually, at the end of the fourth century, in public liturgy and in private amulets trinitarian formulas with both coordinate (to the Father, Son and Holy Spirit) and hybrid formulas (to God through the Son and with the Holy Spirit) became standard doxological expressions (de Bruyn 2017: 221–225).

The success of Constantius in eliminating ousia from the creed, and Julian’s efforts to restore traditional polytheism, caused a new alliance of alarmed bishops to seek common ground to defend the divinity of the Son. While Athanasius had composed an earlier response to the ascendency of the ‘Eusebians’ in his Against the Arians, he only began to defend the language of Nicaea in the 350s in On the Decrees of the Council. Here he presented the Nicene Creed in accord with earlier tradition that excluded the radical teachings of the ‘Eusebians’, and shaped the reception of the creed through his own theological vision of deification and eternal generation (Gwynn 2012: 80–89). In On the Synods, Athanasius continued to cultivate a broader consensus with all those who were not ‘Arians’; and in the Letter to the Antiochenes, he admitted that the confusion about ousia and hypostasis had caused unfortunate division among those who were actually thinking along similar lines of one common nature in the Godhead (Gwynn 2012: 95–98). At this point Nicaea finally became a way to build consensus among the Eastern bishops in defending the divinity of the Son, rather than a dividing line (DelCogliano 2021: 264–267). Athanasius may well have drawn on Eusebius of Caesarea’s explanation of the creed in order to reassure those hesitating that homoousios meant the same as ‘from the nature of the Father’, and did not in fact erase the distinction of the Father and Son as separate hypostases (Ayres 2004a: 350–358).

A new generation of exchanges by Basil of Caesarea, his brother Gregory of Nyssa, and their friend Gregory of Nazianzus concerning divine nature, epistemology, and divine action laid the methodological groundwork for the pro-Nicene doctrine of the Trinity. This reimagining of the radical simplicity of the divine nature in opposition to Aetius and Eunomius, with the aid of Aristotelian and Neoplatonic thought, shifted the earlier and tenacious hierarchical definitions of the Father as first cause to imagine the entire triune Godhead as separate from creation, unified in action, and defined through relation rather than causality. If divine nature was simple by definition, God was incapable of division or degrees of divine existence; generation must happen within this divine simplicity (Ayres 2004b: 279–280). In response to Aetius and Eunomius in particular, the nature of such transcendent divinity must (again by definition) be incomprehensible to created beings, so there can be no final or human comprehension of God. What therefore was revealed in scripture – i.e. the names of God as Father, Son, and Spirit – must be both trustworthy and foundational, and therefore the only foundation for any theological reflection (Ayres 2004b: 282–285). Revelation alone revealed the Godhead as Trinity, and human knowledge must be acknowledged as limited concerning the details of God’s inner life.

Since the names of Father and Son were revealed as constitutive of the simple divine nature, causality was an inadequate key to the Christian doctrine of God. Within its essential simplicity, the names reveal an eternal relation to one another. As Gregory of Nazianzus argued in his Third Theological Oration:

[…] the Father is not a name either of an essence or of an action, most clever sirs. But it is the name of the relation in which the Father stands to the Son and the Son to the Father. […] But let us concede to you that Father is a name of essence: it will still bring in the idea of the Son […]. (Gregory of Nazianzus, Third Theological Oration 16, translated by Browne and Swallow in Hardy and Richardson 1964: 171)

Equally important, the simplicity of divine nature as Father, Son, and Spirit must mean that all persons share in the actions of each, so there is no longer hierarchy or division in the creating, saving, or sanctification of the creation as all these actions reveal the one mystery of the Godhead. Gregory of Nyssa explained, in An Answer to Ablabius:

Rather does every operation which extends from God to creation and is designated according to our differing conceptions of it have its origin in the Father, proceed through the Son, and reach its completion by the Holy Spirit. It is for this reason that the word for the operation is not divided among the persons involved. For the action of each in any matter is not separate and individualized. But whatever occurs […] occurs through the three persons and is not three separate things. (translated by Richardson in Hardy and Richardson 1964: 262)

The result of the necessary epistemological and ontological distinction between creator and creation with regard to language, number, and nature led to the rejection of causality and hierarchy within divinity, which had often been a traditional and cultural assumption within previous Christian theology. In relation to this theology of the unknowable and incomprehensible God, the Cappadocians also developed a spirituality based on the inexhaustible journey of the growth of the soul through love into the boundless intimacy and depths of the divine (Louth 1981: 80–97). The pro-Nicenes thus generated what Lewis Ayres called ‘the grammar of divinity’, i.e. not only creating the theological rules for speaking about God as Trinity but demonstrating how these rules gradually take on a density of theological meaning (Ayres 2004b: 14).

The result of these six decades of close debate and theological reimagining was eventually seen in the theology of the Council of Constantinople in 381, called by Theodosius, which reaffirmed Nicaea. The creed which now is referred to as ‘The Nicene Creed’ is in fact this later synodal statement. During this period, the status and origin of the Holy Spirit had also come into deeper discussion (Hanson 1988: 738–772). Previous scholars had suggested that the definitions of the Spirit had simply been added to the original credal text while eliminating the anathemas against Arius and his supporters, but present opinion supports that certain revisions and enhancements were made (Kelly 1972: 296–305; Ayres 2004a: 253–260). This text, now referred to as the Nicene-Constantinopolitan Creed, was preserved at the Council of Chalcedon in 451 (Hanson 1988: 812–820).

Legislation also followed which outlawed those who taught or met in opposition to this understanding, though non-Nicenes would linger for several centuries in imperial life and empire among the Goths, Burgundians, Suebi, and Vandals (Heil 2014: 85–86). In the next century, the continuing debates over exegesis and the one or two natures of the incarnate Christ, which inflamed ecclesiastical rivalries between Alexandria and Antioch/Constantinople, would eventually split not only the church but also the Byzantine Empire. In the midst of this debate, the Nicene Creed would be introduced into the liturgy as a symbol of orthodoxy. In the seventh century, as an anti-Arian statement, the Western Church added the controversial phrase filioque (and from the Son) describing the procession of the Holy Spirit from the Son and Father rather than from the Father alone; this was and is received as an illegitimate addition to the text by the Eastern Church (Dunn 2021: 350–351).

The lasting legacy of Nicaea was thus not only the first synodal creed, but the intense theological creativity which arose afterward to explicate and defend it. This resulted in the foundational debates to create a methodology for a ‘coherent construction of the entirety of the Christian experience’ (Anatolios 2011: 1, 281–292).

4 Recommended sources for further study

This section offers a non-exhaustive list of primary and secondary sources that may be useful starting points for students and scholars seeking to conduct further study. Readers of all levels may also find the further reading list helpful for deepening their understanding of the topic.

4.1 Collections of primary sources

Opitz, Hans-Georg (ed). 1935. Athanasius Werke. Volume 3, part I. Lieferung 1–2: Urkunden zur Geschichte des arianischen Streites (Athanasius’ Works. Volume 3, part I. Delivery 1–2: Documents on the history of the Arian dispute), 318–328. Berlin: De Gruyter.

Brennecke, Hanns Christof, Uta Heil, Annette von Stockhausen, and Angelika Wintjes (eds). 2007. Athanasius Werke: Dokumente zur Geschichte des arianischen Streites. Volume 3, part I. Lieferung 3: Bis zur Ekthesis Makrostichos (Athanasius’ Works: Documents on the History of the Arian Controversy.Volume 3, part I. Delivery 3: Up to the Ekthesis Makrostichos). Berlin: De Gruyter.

Brennecke, Hanns Christof, Annette von Stockhausen, Christian Muller, Uta Heil, and Angelika Wintjes (eds). 2014. Athanasius Werke: Dokumente zur Geschichte des arianischen Streites. Volume 3, part I. Lieferung 4: Bis zur Synode von Alexandrien 362 (Athanasius' works: Documents on the history of the Desarian dispute. Volume 3, part I. Delivery 4: Up to the Synod of Alexandria 362). Berlin: De Gruyter.

Hardy, Edward R. and Cyril Richardson (eds). 1964. Christology of the Later Fathers. The Library of Christian Classics. Ichthus Edition. Philadelphia: The Westminster Press.

Kinzig, Wolfram, ed. 2017. Faith in Formulae: A Collection of Early Christian Creeds and Creed-Related Texts, 4 vols. Oxford: Oxford University Press.

Radde-Gallwitz, Andrew (ed). 2017. The Cambridge Edition of Early Christian Writings. Volume 1: God. Cambridge: Cambridge University Press.

4.2 Secondary sources

Gwynn, David M. 2007. The Eusebians: The Polemic of Athanasius of Alexandria and the Construction of the ‘Arian Controversy’. Oxford Theology and Religion Monographs. Oxford: Oxford University Press.

Löhr, Winrich. 2006a. ‘Arius Reconsidered (Part 1)’. Zeitschrift für Antikes Christentum 9, no. 3: 524–560.

Löhr, Winrich 2006b. ‘Arius Reconsidered (Part 2)’. Zeitschrift für Antikes Christentum 10, no. 1: 121–157.

Parvis, Sara. 2006. Marcellus of Ancyra and the Lost Years of the Arian Controversy 325–345. Oxford Early Christian Studies. Oxford: Oxford University Press.

Radde-Gallwitz, Andrew. 2023. ‘Nicaea’s Frame: The Organisation of Creedal Knowledge in Late Antiquity and Modernity’. The Intellectual World of Late Antique Christianity. Reshaping Classical Tradition. Edited by Lewis Ayres, Michael W. Champion and Matthew R. Crawford. Cambridge: Cambridge University Press, 221–245.


Copyright Rebecca Lyman (CC BY-NC)


  • Further reading

    • Anatolios, Khaled. 2011. Retrieving Nicaea: The Development and Meaning of Trinitarian Doctrine. New York: Routledge.
    • Ayres, Lewis. 2004b. Nicaea and Its Legacy: An Approach to Fourth-Century Trinitarian Theology. Oxford/New York: Oxford University Press.
    • Ayres, Lewis, and Andrew Radde-Gallwitz. 2009. ‘Doctrine of God’, in The Oxford Handbook of Early Christian Studies. Edited by Susan Ashbrook Harvey and David G. Hunter. Oxford: Oxford University Press, 864–885.
    • Barnes, Timothy D. 2014. Constantine: Dynasty, Religion and Power in the Later Roman Empire. Blackwell Ancient Lives. Chichester: Wiley-Blackwell. Reprint. First published 2011.
    • Behr, John. 2004. The Nicene Faith: Formation of Christian Theology. Crestwood, NY: St Vladimir’s Seminary Press.
    • Ip, Pui Him. 2022. Origen and the Emergence of Divine Simplicity Before Nicaea. Notre Dame: Notre Dame University Press.
    • Kim, Young Richard (ed.). 2021. The Cambridge Companion to the Council of Nicaea. Cambridge: Cambridge University Press.
    • Radde-Gallwitz, Andrew. 2009. Basil of Caesarea, Gregory of Nyssa, and the Transformation of Divine Simplicity. Oxford: Oxford University Press.
    • Vaggione, Richard. 2000. Eunomius of Cyzicus and the Nicene Revolution. Oxford: Oxford University Press.
    • Young, Frances M., and Andrew Teal. 2010. From Nicaea to Chalcedon. A Guide to the Literature and Its Background. Grand Rapids: Baker Academic. Second Edition.
  • Works cited

    • Anatolios, Khaled. 2011. Retrieving Nicaea: The Development and Meaning of Trinitarian Doctrine. New York: Routledge.
    • Ayres, Lewis. 2004a. ‘Athanasius’ Initial Defense of the Term “Homoousios”: Rereading de Decretis’, Journal of Early Christian Studies 12, no. 3: 337–359.
    • Ayres, Lewis. 2004b. Nicaea and Its Legacy: An Approach to Fourth-Century Trinitarian Theology. Oxford/New York: Oxford University Press.
    • Beatrice, Pier Franco. 2002. ‘The Word “Homoousios” from Hellenism to Christianity’, Church History 71, no. 2: 243–272.
    • Behr, John. 2001. The Way to Nicaea: The Formation of Christian Theology. Volume 1. Crestwood, NY: St Vladimir’s Seminary Press.
    • Bowes, Kim. 2008. Private Worship, Public Values, and Religious Change in Late Antiquity. Cambridge: Cambridge University Press.
    • Brakke, David. 1995. Athanasius and the Politics of Asceticism. Oxford: Clarendon Press.
    • de Bruyn, Theodore. 2017. Making Amulets Christian: Artefacts, Scribes, and Contexts. Oxford Early Christian Studies. Oxford: Oxford University Press.
    • DeConick, April. 2020. ‘The One God Is No Simple Matter’, in Monotheism and Christology in Greco-Roman Antiquity. Supplements to Novum Testamentum. Edited by Matthew V. Novenson. Boston/Leiden: Koninklijke Brill, 263–292.
    • DelCogliano, Mark. 2006. ‘Eusebian Theologies of the Son as the Image of God Before 341’, Journal of Early Christian Studies 14, no. 4: 458–484.
    • DelCogliano, Mark. 2018. ‘How Did Arius Learn from Asterius? On the Relationship Between the Thalia and the Syntagmation’, Journal of Ecclesiastical History 69, no. 3: 477–492.
    • DelCogliano, Mark. 2021. ‘The Emergence of the Pro-Nicene Alliance’, in The Cambridge Companion to the Council of Nicaea. Edited by Young Richard Kim. Cambridge: Cambridge University Press, 256–281.
    • Drake, Hal. 2021. ‘The Elephant in the Room: Constantine at the Council’, in The Cambridge Companion to the Council of Nicaea. Edited by Young Richard Kim. Cambridge: Cambridge University Press, 111–132.
    • Dunn, Geoffrey. 2021. ‘Catholic Reception of the Council of Nicaea’, in The Cambridge Companion to the Council of Nicaea. Edited by Young Richard Kim. Cambridge: Cambridge University Press, 347–367.
    • Edwards, Mark. 1998. ‘Did Origen Apply the Word “Homoousios” to the Son?’, Journal of Theological Studies 49: 658–670.
    • Edwards, Mark. 2002. Origen Against Plato. Ashgate Studies in Philosophy and Theology in Late Antiquity. Aldershot: Ashgate Publishing Limited.
    • Edwards, Mark. 2015. Religions of the Constantinian Empire. Oxford: Oxford University Press.
    • Edwards, Mark. 2021. ‘The Creed’, in The Cambridge Companion to the Council of Nicaea. Edited by Young Richard Kim. Cambridge: Cambridge University Press, 135–157.
    • Ferguson, Everett. 2008. ‘Creeds, Councils and Canons’, in The Oxford Handbook of Early Christian Studies. Edited by Susan Ashbrook Harvey and David G. Hunter. Oxford: Oxford University Press, 428–429.
    • Fredriksen, Paula. 2020. ‘How High Can High Christology Be?’, in Monotheism and Christology in Greco-Roman Antiquity. Supplements to Novum Testamentum. Edited by Matthew V. Novenson. Boston/Leiden: Koninklijke Brill, 293–319.
    • Gavrilyuk, Paul L. 2006. The Suffering of the Impassible God. The Dialectics of Patristic Thought. Oxford Early Christian Studies Oxford: Oxford University Press.
    • Gwynn, David. 2007. The Eusebians: The Polemic of Athanasius of Alexandria and the Construction of ‘The Arian Controversy’. Oxford: Oxford University Press.
    • Gwynn, David. 2012. Athanasius of Alexandria: Bishop, Theologian, Ascetic, Father. Christian Theology in Context Oxford: Oxford University Press.
    • Gwynn, David. 2021. ‘Reconstructing the Council of Nicaea’, in The Cambridge Companion to the Council of Nicaea. Edited by Young Richard Kim. Cambridge: Cambridge University Press, 90–101.
    • Haas, Christopher. 1997. Alexandria in Late Antiquity: Topography and Social Conflict. Baltimore/London: Johns Hopkins University Press.
    • Hanson, Richard P. C. 1988. The Search for the Christian Doctrine of God. The Arian Controversy 318–381. Edinburgh: T&T Clark.
    • Hardy, Edward R., and Cyril Richardson. 1964. Christology of the Later Fathers. Library of Christian Classics Philadelphia: The Westminster Press.
    • Hengstermann, Christian. 2022. ‘The Three Hypostases in Origen: Salvation Trinitarianism’, in The Oxford Handbook of Origen. Edited by Ronald E. Heine and Karen Jo Torjesen. Oxford: Oxford University Press, 325–354.
    • Heil, Uta. 2014. ‘The Homoians’, in Arianism: Roman Heresy and Barbarian Creed. Edited by Guido M. Berndt and Roland Steinacher. Farnham: Ashgate Publishing Company, 85–116.
    • Ip, Pui Him. 2022. Origen and the Emergence of Divine Simplicity Before Nicaea. Notre Dame: Notre Dame University Press.
    • Jacobs, Inge. 2021. ‘Hosting the Council of Nicaea. Material Needs and Solutions’, in The Cambridge Companion to the Council of Nicaea. Edited by Young Richard Kim. Cambridge: Cambridge University Press, 65–89.
    • Johnson, Aaron. 2021. ‘Narrating the Council: Eusebius on Nicaea’, in The Cambridge Companion to the Council of Nicaea. Edited by Young Richard Kim. Cambridge: Cambridge University Press, 202–222.
    • Kelly, J. N. D. 1972. Early Christian Creeds. London: Longman. 3rd edition.
    • King, Karen. 2008. ‘Which Early Christianity?’, in The Oxford Handbook of Early Christian Studies. Edited by Susan Ashbrook Harvey and David G. Hunter. Oxford: Oxford University Press, 66–85.
    • Kinzig, W., and M. Vinzent. 1999. ‘Research on the Origin of the Creed’, Journal of Theological Studies 50: 535–559.
    • Lienhard, Joseph. 1987. ‘The “Arian” Controversy: Some Categories Reconsidered’, Theological Studies 48: 415–437.
    • Lim, Richard. 1995. Public Disputation, Power, and Social Order in Late Antiquity. Berkeley: University of California Press.
    • Löhr, Winrich. 2006a. ‘Arius Reconsidered (Part 1)’, Zeitschrift Fur Antikes Christentum 9, no. 3: 524–560.
    • Löhr, Winrich. 2006b. ‘Arius Reconsidered (Part 2)’, Zeitschrift Fur Antikes Christentum 10, no. 1: 121–157.
    • Louth, Andrew. 1981. The Origins of the Christian Mystical Tradition: From Plato to Denys. Oxford: Clarendon Press.
    • Lyman, Rebecca. 2021. ‘Arius and Arianism: The Origins of the Alexandrian Controversy’, in The Cambridge Companion to the Council of Nicaea. Edited by Young Richard Kim. Cambridge: Cambridge University Press, 43–62.
    • MacMullen, Ramsay. 2006. Voting About God in Early Church Councils. New Haven: Yale University Press.
    • McCarthy, Daniel P. 2021. ‘The Council of Nicaea and the Celebration of the Christian Pasch’, in The Cambridge Companion to the Council of Nicaea. Edited by Young Richard Kim. Cambridge: Cambridge University Press, 177–201.
    • Novenson, M. (ed.). 2020. Monotheism and Christology in Greco-Roman Antiquity. Supplements to Novum Testamentum. Boston/Leiden: Koninklijke Brill.
    • Opitz, Hans-Georg (ed.). 1935. Athanasius Werke. Volume 3, part I. Lieferung 1–2: Urkunden zur Geschichte des arianischen Streites, 318–328. Berlin: De Gruyter.
    • Parvis, Sarah. 2006. Marcellus of Ancyra and the Lost Years of the Arian Controversy 325–345. Oxford Early Christian Studies Oxford: Oxford University Press.
    • Parvis, Sarah. 2021. ‘The Reception of Nicaea and Homoousios to 360’, in The Cambridge Companion to the Council of Nicaea. Edited by Young Richard Kim. Cambridge: Cambridge University Press, 225–255.
    • Radde-Gallwitz, Andrew. 2023. ‘Nicaea’s Frame: The Organisation of Creedal Knowledge in Late Antiquity and Modernity’, in The Intellectual World of Late Antique Christianity. Reshaping Classical Tradition. Edited by Lewis Ayres, Michael W. Champion, and Matthew R. Crawford. Cambridge: Cambridge University Press, 221–245.
    • Shin, Min Seok. 2018. The Great Persecution: A Historical Re-Examination. Studia Antiqua Australiensia Turnhout: Brepols Publishing.
    • Vaggione, Richard. 2000. Eunomius of Cyzicus and the Nicene Revolution. Oxford: Oxford University Press.
    • Vinzent, Marcus. 2016. ‘Embodied Early and Medieval Christianity: Challenging Its “Canonical” and “Institutional Origins”’, Religion in the Roman Empire 2, no. 1: 103–124.
    • Weckwerth, Andreas. 2021. ‘The Twenty Canons of the Council of Nicaea’, in The Cambridge Companion to the Council of Nicaea. Edited by Young Richard Kim. Cambridge: Cambridge University Press, 158–176.
    • Wiles, Maurice. 1996. Archetypal Heresy: Arianism Through the Centuries. Oxford: Oxford University Press.
    • Williams, Daniel. 2021. ‘The Council of Ariminum (359) and the Rise of the Neo-Nicenes’, in The Cambridge Companion to the Council of Nicaea. Edited by Young Richard Kim. Cambridge: Cambridge University Press, 305–324.
    • Williams, Michael. 1996. Rethinking Gnosticism: An Argument for Dismantling a Dubious Category. Princeton: Princeton University Press.
    • Williams, Rowan. 1989. ‘Does It Make Sense to Speak of Pre-Nicene Orthodoxy?’, in The Making of Orthodoxy: Essays in Honour of Henry Chadwick. Edited by Rowan Williams. Cambridge: Cambridge University Press, 1–23.
    • Williams, Rowan. 2001. Arius: Heresy and Tradition. London: Darton, Longman, and Todd. First published 1987.
    • Young, Frances M. 2008. ‘The Interpretation of Scripture’, in The Oxford Handbook of Early Christian Studies. Edited by Susan Ashbrook Harvey and David G. Hunter. Oxford: Oxford University Press, 845–863.

Academic tools