2 Life
While the writings of Eusebius influenced later Christian thought profoundly, his works were composed in response to the events of his own life and time. It seems that Eusebius was born between 260 and 264 based on the events recorded in his Ecclesiastical History (HE; Schwartz 1907: col. 1370–1371), though there is little evidence which suggests where – scholars often assume in Caesarea Maritima, a city in Roman Palestine (for biographical details, see Morlet 2012: 3–12). Little is known of Eusebius’ personal life or ministry before the turn of the fourth century, other than the identity of his teacher, Pamphilus. Eusebius’ reverence for his teacher is evident in the assumption of his name: Eusebius Pamphili, or son of Pamphilus (Wallace-Hadrill 1960: 11; concerning Pamphilus, see HE 6.32.3, 7.32.25–27, 8.13.6; Martyrs of Palestine [MP] 11). In 303–304, several imperial edicts were enacted which targeted Christianity, eventually resulting in harsh persecution against Christians throughout the Roman Empire (Barnes 1981: 22–39; Lactantius, De Mortibus Persecutorum 13.1; HE 8.5.1, 8.2.5, 8.3.1–4; MP 3.1 LR). Eusebius travelled across Tyre, Egypt, and Caesarea during this period and wrote as a firsthand witness to these events:
[W]e saw with our own eyes buildings containing the places of prayer smashed from their roofs down to their very foundations, and the inspired and sacred writings thrown into fires in the middle of the agoras, and the shepherds of the churches, some shamefully hiding out here and there, others humiliatingly captured and mocked by the enemies. (HE 8.2.1)
Amidst the persecution, Pamphilus was imprisoned in 307 and martyred in 309 or 310 (HE 6.33.4; MP 7.5–6). Eusebius apparently had access to Pamphilus in prison, as they worked together on the Defence of Origen (308–310) there, and Eusebius apparently added a sixth book after his teacher’s death (for discussion, see Morlet 2011: 8; Photius, The Library 118; Jerome, On Illustrious Men 75.4. The dates of most of Eusebius’ works are contested; this article draws from Morlet 2012).
Christians were allowed to freely worship across the Roman Empire in 313 after a summit between Constantine and Licinius (HE 10.5.1–14; Lactantius, De Mortibus Persecutorum 48). Shortly after, in 314 or 315, Eusebius became bishop in Caesarea Maritima (HE 10.4). In the coming years, Eusebius would be caught up in the ‘Arian’ controversy, which could have originated as early as 318 or as late as 323 (see Fernández 2024, Fontes Nicaenae Synodi [FNS] xxiii–xxxiv). A presbyter named Arius was excommunicated by his bishop, Alexander of Alexandria, for teaching what Alexander deemed to be heretical trinitarian doctrine (FNS 26). In response, Arius sent messengers to Eusebius and other sympathetic bishops asking for permission to continue to lead services. According to fifth-century historian Sozomen, Eusebius and several other bishops met at a synod in Palestine and granted Arius’ petition – with an important caveat. They could hold services as before, but Arius must ‘be obedient to Alexander, continually seek peace, and partake in fellowship with him’ (Opitz 1934: Dok. 8; Urk. 10; Hanson 1988: 135). Around the same time, Eusebius composed a letter to Alexander scolding him for misreading Arius’ theology (FNS 12.3).
In September 324, Constantine unified the Roman Empire after defeating his Eastern rival, Licinius. Upon assuming power, Constantine sought to intervene in the ‘Arian’ controversy by calling an ecumenical council at Nicaea. In the months preceding, Eusebius attended a synod in Antioch in the spring of 325, which included key Nicene figures Ossius of Cordova and Eustathius of Antioch (see Simperl 2025). Eusebius was excommunicated there for opposing the proposed anti-Arian creed, along with two of his allies, Theodotus of Laodicea and Narcissus of Neronias (Luibhéid 1981: 46–51), though he was given a chance to repent at the subsequent council in Nicaea (FNS 28.15).
The Council of Nicaea met several months later in May or June 325, a defining moment in the life of the Christian church and in Eusebius’ own career (see Lyman 2024). Unfortunately, the Acta (official recorded proceedings) for the council, if it ever existed, is lost. Thus, the reconstruction of the council’s proceedings is restricted to its creed and canons, along with several letters and later accounts from ecclesiastical writers, including Eusebius (Letter to the Caesarean Church, FNS 37; Vita Constantini [VC] 3.4–14). Eusebius’ own status at the council was precarious, especially as his recent excommunication in Antioch surely loomed large at the council. During the proceedings, Eusebius was given a chance to prove his orthodoxy, which he demonstrated through the presentation of a creed from Caesarea, thereby prompting his reinstatement. It has been proposed by some scholars that the Eusebian Creed provided the framework and basis of the Nicene Creed, although this is unlikely for a variety of reasons (Parvis 2006: 83–89; Behr 2004: I.155–156). Further, there are some questions about the manner of Eusebius’ reinstatement in connection to his creed. Eustathius of Antioch, one of the bishops who had previously deposed Eusebius in Antioch, discusses the ‘blasphemy’ of a Eusebius at Nicaea:
As the form of the faith was sought, the writing was brought forward, a manifest proof of Eusebius’ blasphemy. And, when the [writing] had been read aloud to everyone, immediately it produced uncertainty in the hearers because of its deviation, and it inflicted irredeemable shame on the writer. (FNS 39)
The pertinent question is: which Eusebius does Eustathius mention here – Eusebius of Nicomedia or Caesarea, both attendees of the council? Scholars are divided: most argue that Eusebius of Nicomedia is the more probable person under scrutiny here (Stead 1973: 92–100; Hanson 1988: 171–179), but others have claimed the Caesarean is also possible (Fernández 2023: 97–122; 2025: 191–204). Either way, Eusebius of Caesarea eventually signed the Nicene Creed, which he discussed in a letter to his diocese. The council condemned Arius and several Libyan bishops, and Eusebius of Nicomedia and Theognis of Nicaea were excommunicated shortly after.
The years after the council are marked by confusion and ecclesiastical disunity. Arius was formally reinstated in late 327 or early 328, along with Eusebius of Nicomedia and Theognis, at a council in Nicaea or Nicomedia which Eusebius of Caesarea may have attended (VC 3.23). Eusebius likely participated in the deposition of several key supporters of the council of Nicaea, namely Eustathius of Antioch at the council of Antioch in late 328 and Athanasius of Alexandria in 335 at the Council of Tyre. In 335 or 336, another council met in Constantinople to address the theology of Marcellus of Ancyra. Marcellus was an ally to Eustathius and Athanasius, and his work Against Asterius attacked the ‘Eusebians’, including Eusebius of Caesarea (Lienhard 1999: 47–68). Eusebius wrote and presented Against Marcellus (336) after the council and followed it with On Ecclesiastical Theology (337) to defend his orthodoxy and condemn Marcellus. Interestingly, despite his role in the deposition of these figures, Eusebius is not named as one of the ‘Eusebians’ seeking to displace Nicene supporters in Athanasius’ account of the events (Gwynn 2007: 83–87).
Late in his life, Eusebius wrote several works related to Constantine’s political activity. He delivered speeches at the dedication of two imperially supported churches in late 335 and 336, the Church of the Holy Sepulchre at Jerusalem and its namesake in Constantinople. At the Tricennalia of Constantine in 336, the thirty-year celebration of the emperor’s reign, Eusebius delivered the flattering speech, In Praise of Constantine. Sometime in the following year, he wrote The Life of Constantine after the emperor’s death. Eusebius likely died in 339 or 340 (Morlet 2011: 12).
3 Intellectual milieu: fourth-century scholarship
There are several key developments in philosophy in the second and third century which shaped the fourth-century Christian intellectual culture Eusebius engaged in. First, in addition to the intellectual centres in Athens or Rome, new centres emerged in Syrian Edessa, Antioch, and Alexandria (LaValle Norman 2019: 51). Second, Christians and non-Christian philosophers were not in isolation from one another, nor were they always in opposition. In one example, it is possible that three of the most influential thinkers of the third century – the Christian, Origen of Alexandria, and his ‘pagan’ counterparts, Cassius Longinus and Plotinus – shared a teacher, Ammonius Saccas (for two sides of this contested issue, see Digeser 2010; Edwards 2015). Despite the cross-pollination of ideas between religious groups, some non-Christian writers, such as Celsus and Porphyry of Tyre, developed critiques of Christianity which demanded a response from Christian intellectuals. Third, a creative mixture of metaphysics, theology, and mysticism began to develop through Plotinus, Porphyry, and Iamblichus, which became influential for later Christians such as Augustine and Pseudo-Dionysius. These thinkers are often identified with the ‘Neoplatonic’ school of thought (in modern coinage) for their employment and self-identification with Plato’s views, though they appropriated and harmonized almost all of Hellenic religion, philosophy, and literature into a robust system. These ‘schools’ should not be understood in the sense of a modern university, nor as if they shared a coherent and common framework. While influential, they were modest and small, diverse in students and curriculum, and the core of the school was the current teacher (Cribiore 2005).
Eusebius inherited ideas from many of these philosophers, especially through the writings of Origen of Alexandria and Pamphilus, and their mode of intellectual inquiry. He combats philosophical critiques of Christianity and develops resources to train Christian thinkers, not unlike the work of some of his rivals in antiquity. In his writings which directly engage with philosophers, Eusebius frames Christianity as a rival and victor over non-Christian philosophical frameworks and schools, the ‘true philosophy’ as it was derived from the ‘true teacher’, the eternal Logos. In this, Eusebius develops a robust intellectual programme which aided in a blossoming culture of Christian intellectualism (for more background, see Christianity and Graeco-Roman Paganism).
3.1 Intellectual programme
Eusebius’ writings span numerous and diverse genres, with some that defy classification. In Preparation for the Gospel (313–317), for instance, Eusebius quotes many works from ancient and contemporary philosophers, poets, and historians, demonstrating a deep familiarity with Hellenistic literature and culture. As Johannes Quasten notes: ‘Except for Origen, Eusebius outdistances all Greek Church Fathers in research and scholarship’ (1990: 311).
With Eusebius’ entire corpus in mind, Elizabeth C. Penland has argued it is best to view him as a teacher at a Christian philosophical school, not unlike Plotinus or others (Penland 2011: 87–97). This becomes plausible when considering how many of his works are specifically designed for instruction. Eusebius claims his Preparation for the Gospel [PE] is an ‘elementary instruction and introduction’ (PE 1.1.12) to the faith, and his General Elementary Introduction (303–313) teaches pupils how to read the scriptures, encouraging a christocentric reading of the historical books of the Old Testament. This type of literature is not completely unique – other philosophical schools created these introductory books to orient students to the profession. Aaron Johnson even argues that General Elementary Introduction might have been written with a competing school in mind, that of Porphyry of Tyre (Johnson 2011: 99–118). Porphyry drew the bishop’s attention for his massive Against the Christians, a critique of Christian teaching and the scriptures. Eusebius met his critique with a (now lost) work called Against Porphyry (Jerome, On Illustrious Men 81.2), and framed Christianity as a competitor to non-Christian philosophical schools like Porphyry’s, ‘a new and true kind of divine philosophy’ (PE 1.5).
While Eusebius develops a robust pedagogical programme in his writings, the evidence concerning a physical ‘school’ or ‘library’ in Caesarea is wanting. Eusebius himself seemed to be a student in a sort of philosophical school under the tutelage of Pamphilus, who acquired a small group of people to engage in learning together (MP 4.6–7). Eusebius emphasizes Pamphilus’ debt (and his own) to the work and thought of Origen of Alexandria, an influential Christian teacher of the third century, who wrote foundational works in hermeneutics, exegesis, and theology. Apparently, Pamphilus acquired many of Origen’s works (HE 6.32.3). In his Ecclesiastical History, Eusebius frames Pamphilus’ school as the continuation of Origen’s, a Caesarean offshoot of the Alexandrian one (Penland 2013).
While the pedagogical nature of his writings demonstrates an interest in training others, Eusebius does not mention the continuation of the school past Pamphilus’ martyrdom nor any students of his own. Further, he does not provide much information about the contents of his library, though it is possible he inherited Pamphilus’ collection of Origen’s works. Andrew Carriker (2003) has used Eusebius’ excessive and lengthy citations in his works to catalogue his ‘library’, but this might exaggerate the number of volumes at his disposal. To cite a source is not to have immediate access to it and Eusebius’ citations are not without apologetic purpose – he is, perhaps, ‘performing erudition’ and creating the image of a library in his works to establish ‘control of Greek culture’ (Inowlocki 2011: 223). It is likely that the legend surrounding the library of Caesarea, beginning with the praise of Jerome and Isidore of Seville, has exaggerated its contents, since there is no evidence of a library there persisting after Eusebius’ time (see Inowlocki 2024). Whether Eusebius taught students directly or had a large library, it is clear is that Eusebius engaged in scholarship related to ‘Scripture, pagan and Christian history, ancient literature, philosophy, geography, technical chronology, exegesis, philology and palaeography’ (Quasten 1990: 311), and created works intended to inform and train his readers.
3.2 Relationship to philosophy
Eusebius directly engages with philosophy at length in several of his apologetic works, most substantially in Preparation for the Gospel, Theophany, and Against Hierocles. Eusebius demonstrates a deep familiarity with certain philosophical traditions, especially Platonism and Stoicism, as well as a creativity in his employment and discussion of philosophy (Morlet 2024: 23–50). Throughout, Eusebius follows a tradition of Christian thinkers like Clement and Origen of Alexandria who expresses great admiration for Plato, esteeming him ‘as a friend above all the Greeks’, ‘whose sentiments are dear and congenial’ to himself (PE 13.18). Nevertheless, Eusebius is often critical of philosophers, including Plato, using their intellectual disunity to critique paganism (e.g. PE 1.8, 3.17, 13.14–21; Theophany 2.30). One of Eusebius’ main philosophical interlocutors is Porphyry of Tyre, particularly in his Against Christians. In the Preparation, for instance, Porphyry is the second most quoted philosopher behind Plato. This has sometimes led to the scholarly argument that all of Eusebius’ apologetic works are focused on undermining Porphyry’s critique of Christianity (e.g. Fiedrowicz 2001: 73). While Eusebius did write a direct response to this work, this is a reductive picture of Eusebius’ philosophical and apologetic aims (Morlet 2009: 277; 2011).
Preparation for the Gospel is a massive fifteen-book work that served as a defence of Christianity against non-Christian critiques by arguing all truths possessed by philosophers were taken from the Hebrews (PE 10.4.31, 12.1.1). Aaron Johnson has shown that Eusebius also wrote this work constructively as ‘a lengthy literary seminar on the history of thought’, teaching the various tenets of Platonic philosophy through his lengthy primary source quotations (Johnson 2024: 158). His Theophany (before 333) is a more focused apologetic work, though with many of the same themes as the Preparation. Therein, the chief focus is the incarnation, especially connecting the creative work of Christ to humanity’s need for the incarnation, especially as they fell into irrationality. Eusebius argues humanity needed an embodied teacher to bring them back to God. Against Hierocles (311–313) is a different sort of apologetic text, insofar as it answers a particular anti-Christian argument in which Apollonius of Tyana, a non-Christian holy man, is compared to Christ. While long assumed to be penned by Eusebius, the authorship of Against Hierocles has been recently contested by Tomas Hägg and Aaron Johnson (see Montinaro and Neumann 2018).
While scripture is undoubtedly the most important source for Eusebius’ understanding of God and the world, philosophy also may play a central role. Friedo Ricken, in a foundational article, compares Eusebius’ Logos theology to philosophical texts from the middle Platonic period, a phase of thought indebted to Plato from around 130 BCE to the formation of Neoplatonism after 250 CE. He argues Eusebius’ titles for God, emphasis on creation’s inability to know the transcendent God, and role of a mediator mirrors the framework of Numenius of Apamea and Plutarch of Chaeronea, two important middle Platonic philosophers (Ricken 1967). Ricken, therefore, concludes that Eusebius is directly influenced by middle Platonic cosmology. Other scholars have followed Ricken on this (e.g. Des Places 1971: 462), though there has been some debate over how much Eusebius modified this philosophy according to scripture (Lyman 1993: 99). Viewed as a whole, it seems inevitable that Platonic ideas shaped Eusebius’ thought, especially when considering how steeped in the literature he was. But importantly, his own identity is also shaped in juxtaposition to philosophers and philosophy – the Christian religion is superior to them:
And before all things we shall show that not from ignorance of the things which they admire [Greek philosophy], but from contempt of the unprofitable study therein we have cared very little for them, and devoted our own souls to the practice of things far better [Christianity]. (PE 15, preface)
4 Political theology
Until the turn of the fourth century, Christianity was looked upon with suspicion by the Roman state, which led to certain restrictions and local persecutions throughout. Not every Roman emperor was directly hostile towards Christianity, though, especially when considering some periods of toleration (most significantly the ‘little peace’ of the church in the third century under Gallienus, during which it is possible that Christianity was legalized for a time) and the documented legalization of Christianity in 313 by Licinius and Constantine. From the earliest extant Christian writings, such as the Epistle to the Romans and the book of Revelation, followers of Jesus Christ had reflected on Christianity’s relationship to the Roman Empire, even appealing to the emperor at times for fair treatment. Few had considered the theological and political implications of a Christian emperor, however; the conversion of Constantine in 312 was an unprecedented shift for all Christians under Roman rule. Eusebius’ narration of these events made sense of these political changes in theological ways, foregrounding the sovereignty of God in Constantine’s conversion, his ascent to power over all of Rome in 324, and the manner of his rule. As a result of Eusebius’ writings, imperial sovereignty was frequently considered in light of God’s sovereignty for the next millennia.
4.1 Relationship to Constantine
Late in his life, Eusebius unapologetically praises Constantine and imperial Christian rule: ‘Constantine, alone among all those who have ruled the Roman Empire, became a friend of the all-sovereign God and was established as a clear example to all mankind of the life of godliness’ (VC 1.3.4). In the late nineteenth century through the mid-twentieth century, Eusebius’ praise was met with scathing criticism by systematic theologians and patristic scholars alike. So, Erik Peterson claims that Eusebius is a ‘political publicist’ (1951: 91), a court theologian using theology to justify Constantine’s reign. More recently, beginning largely with T. D. Barnes and Michael Hollerich, patristic scholarship nuanced this portrait, arguing instead that Eusebius’ political theology is not as positive or uncritical as once believed, even if Eusebius frames Constantine as God’s chosen ruler (Barnes 1981; Hollerich 1999; Johannessen 2016).
Eusebius likely encountered Constantine only five times in his lifetime, mostly at councils and when giving speeches (Barnes 1981: 266). Constantine and Eusebius did correspond through several letters – the emperor wrote to the bishop six times that we know of, though only three were written to Eusebius individually. Of these three, the first commends the bishop for refusing to take the vacant see in Antioch (VC 3.61.1–2), the second extends gratitude for sending a treatise on Easter called On Pascha (333–335) (VC IV.35; DelCogliano 2011: 39–68), and the third requests that Eusebius prepare fifty copies of the scriptures for the churches throughout the imperial city (VC 4.35).
If Eusebius was never part of his court and seldom encountered the emperor, why has he been considered a ‘court theologian’, as described by Peterson? It is because he portrays himself as having a personal and prominent relationship with Constantine, one built on respect and mutual admiration. He writes himself into The Life of Constantine (after 337), recording his correspondences with Constantine which display the ‘great admiration’ the emperor had for Eusebius’ learning (VC 4.35.2–3). By placing these letters and encounters throughout the narrative, Eusebius frames himself as an important part of Constantine’s reign. The irony, here, as noted by Devin Singh, is that many recent scholars of Eusebius have sought to demonstrate the distance between the bishop and Constantine to overcome the ‘court theologian’ stereotype – the very stereotype that Eusebius painted for himself (Singh 2013).
4.2 Theology of Christian political power
Eusebius’ theology of political power must be contextualized amidst his other writings. While he frames himself as a friend of Constantine in the Life, he only mentions the emperor and the Roman Empire in passing in his biblical commentaries and theological works. He does develop a political theology, though – or rather a theology that incorporates the role of the empire – in several works: Life of Constantine, In Praise of Constantine (336), parts of Ecclesiastical History (312), and Oration on Christ’s Sepulchre (335–336). In each, Eusebius writes in a tradition of aligning divine favour with the current ruler; but he boldly shapes Constantine as a copy of the true king, placing God as the centre of his political vision.
In Praise of Constantine [LC] is a speech delivered in July 336 for the Emperor’s thirtieth jubilee in Constantinople. In this work, Eusebius reflects on the nature of God, the Sovereign one, in connection with the earthly emperor, claiming that the jubilee is foremost ‘a celebration of the Supreme Sovereign […] the One who is Above the Universe’ (LC 1.1). Much of the focus of this work is on the Logos, that is the Son of God, who orders and guides the universe for the Father – Constantine is a copy of this Logos, imitating him in his actions (LC 2.1–5; 4.4). The Oration on Christ’s Sepulchre [SC] was originally edited together with In Praise of Constantine, though it is clearly a separate oration delivered in Jerusalem in 335 (Drake 1976: 30–45). Therein, Eusebius responds to a non-Christian criticism concerning imperial support in the construction of the Church of the Holy Sepulchre, in which he justifies the Christian activity of Constantine. Likewise, a Logos theology is employed throughout (SC 11.8–12, 16), but nowhere is Constantine compared to the Logos as in In Praise of Constantine.
Life of Constantine is unique from these other works, especially in genre: it is a unique blend of panegyric, life, and a history (Cameron and Hall 1999: 27–34). It was written after Constantine’s death and records his military achievements, religious rule and policies, and his personal life. While it is the most detailed source on Constantine from antiquity, it has often been critiqued for its overly flattering portrait of the emperor (Barnes 1981: 267).
Eusebius’ political theology is explicitly monotheistic: the one sovereign God requires one king over the earth. ‘There is one Sovereign, and His Logos and royal law is one’ (LC 3.6), and thus the heavenly kingdom is monarchical. Constantine imitates this kingdom, piloting ‘affairs below with an upward gaze’, growing ‘strong in his model of monarchic rule’ (LC 3.5). The Logos plays a special role in this model as the one who ‘directs the helm and sets straight all things on earth’ (LC 1.6). In chapter 2 of In Praise of Constantine, Eusebius discusses how Constantine copies the activity of the Logos, though in a limited capacity: both have long reigns, make their kingdom fit for the Father, subdue their opponents, bring their peoples to knowledge of God, and abolish godless error. In other words, Constantine imitates the rule of the Logos through his political activity and virtuous life, as an earthly sovereign should.
This sort of political theology is not new: it has similarities with philosophical texts from the Neopythagorean school, named after those who emphasized the writings of Pythagoras and Plato in the late Hellenistic period (Chesnut 1978). However, Eusebius’ work is novel in several ways. First, Eusebius focuses far more on God than the emperor throughout In Praise of Constantine, which is quite bold considering Constantine was in the audience. The emperor’s virtues are expounded upon primarily to show affinity to the Logos, and his victories are more frequently framed as spiritual rather than military triumphs (LC 2.1–5). In other words, God is the primary ‘hero’ of the speech, even while it praises the emperor. Second, in Life of Constantine, Eusebius casts Constantine in a discernibly scriptural light, most famously by comparing him to Moses (VC 1.12; 1.20; 1.38; 2.11–12). While he only explicitly links Constantine to Moses in four ways, the language throughout the narrative invites readers to think about Constantine in scriptural terms (Damgaard 2013).
While Eusebius praises Constantine in these works, one must be careful when framing his political theology. First, it is the logic of God’s sovereignty and providence that are the primary factors in his political theology, rather than opportunism or unrestricted optimism about Constantine’s reign (Johnson 2006: 153–197; Fédou 2013: 114–115; Johannessen 2016: 171–202). Second, as noted by Christopher Bonura (2021), Eusebius does not frame Rome under Constantine as the eschatological kingdom of God. The Christian emperor’s ascent to power does not mark the end of God’s activity but looks forward to the kingdom (LC 5.5). Finally, Constantine is not the only copy of the Logos; all Christians who participate in the Logos to overcome vice through reason are said to be copies of the Son of God (LC 4). Eusebius’ political theology is very positive about Christian political power, but not blindingly so.
Eusebius’ political theology has an important legacy in the medieval period in connecting God’s sovereignty to Christian rulers. Thus, in an important article, Norman H. Baynes claims Eusebius’ ‘political philosophy of the Christian Empire […] was consistently maintained throughout the millennium of Byzantine absolutism’ (Baynes 1955: 168). For this, Eusebius has been called the ‘father of Caesaropapism’, a view which marries political power with religious power, for viewing an emperor as God’s chosen representative to rule (Sansterre 1972: 131–195).
5 A theology of history and the Word
The writers of the Christian scriptures narrated God’s work in history, explaining events and movements in light of divine providence. So, biblical writers ascribe military defeats and victories to God’s judgment or favour (e.g. Exod 14:13–14; Josh 6:2–5), Stephen traces God’s hand in the history of Israel from Abraham to the rejection of the Messiah (Acts 7), and the gospel accounts of Christ’s life and teachings are laid out in a type of historical narrative, with God working in and through Jesus. Early Christian chroniclers, such as Hegesippus and Sextus Julianus Africanus, followed the gospel writers and the Acts of the Apostles in this historical work. But no ecclesiastical writer in late antiquity had yet accomplished the comprehensive vision of Eusebius in the composition of the Chronicle and Ecclesiastical History, which incorporate the scriptures, ‘pagan’ history, and ‘church’ history into a unified narrative of God’s providential work. In this, the implicit aim of Eusebius’ historical and biblical scholarship is to teach Christians how to read God’s work in the scriptures and Christian history, especially considering the recent shifts in the Roman Empire (e.g. HE 1.2.23; Demonstration of the Gospel [DE] 3.7), through the creation of innovative study tools and genre-defying works. But Eusebius also had contemporary apologetic aims in mind. In the ancient Roman world, national identity was tied to its history, to the sacred texts and the important figures who lived therein; history is not only a narrative of the past, but identity formation for a particular group, delineating the boundaries of its people, virtues, and priorities (Johnson 2006). Eusebius composes the Ecclesiastical History with this in mind, giving his fourth-century audience a particular window into the past by prioritizing the people and events that conformed to certain Roman values while glossing over some other strands of Christianity in the early church, such as those represented in the Nag Hammadi Codices (Corke-Webster 2019: 216). In sum, Eusebius’ historical and biblical scholarship shaped discourse about the nature of the scriptures, Christian identity, and the history of the church in the early fourth century and in the centuries to come.
5.1 Historical scholarship
Eusebius is sometimes called the ‘father of church history’ for the Chronicle (editions from 311), Ecclesiastical History, and Life of Constantine. These works, particularly Ecclesiastical History, are still the chief source for early Christian history, providing a wealth of insights into the growth and development of the ancient church. Eusebius’ omissions, errors, and framing of early Christianity are also the cause for scholarly debate, however, with discussions concerning the accuracy of his citations (Andrei 2012: 69–76) and how distorted a picture of the early church readers are presented with (for discussion, see Hollerich 2021: 250–268).
The Ecclesiastical History is a narrative retelling of the ‘successions from the holy apostles’, important events, prominent leaders and teachers, infamous heretics, the sufferings of the Jews, and heroic Christian martyrs found in the first three centuries of the church (HE 1.1.1). While Eusebius is indebted to earlier Christian chroniclers such as Julianus Africanus and Hegesippus in the composition of his Ecclesiastical History, he notes how unique this work is: no other ecclesiastical writer had ‘devoted his attention to this kind of writing’ (HE 1.1.5–6). Part of his aim is apologetic. He wishes to show how Christianity – which he frames as a ‘new nation’ – is divinely instituted (e.g. HE 1.2.23). Thus, he begins with Christ’s preexistent nature in book one before moving to his action in the world (HE 1.1.2). Part of what makes this work unique is the selective interjection of lengthy primary source quotations, often without further remark or explanation. In a modern sense, this not only makes the Ecclesiastical History a narrative, but a sort of ‘source reader’ for his audience.
The Chronicle aims to provide a universal chronology of ancient history, charting out important dates and figures in five societies from Abraham to 325 CE (Mosshammer 1979). The first book provides a unique mixture of narrative and a list of rulers, intellectual figures, important texts, wars, and even victorious athletes. The second book is a series of columns which synchronizes the data discussed in the first book, placing contemporaneous figures and events from across societies alongside one another. In other words, it weaves distinct historical threads into a single tapestry which allows readers to note historical events occurring in different kingdoms during the same period. There are two significant apologetic and theological aims which are accomplished by this work. First, the dating system used to coordinate the kingdoms is the Abrahamic one, which grounds all history in Christian history (Grafton and Williams 2006: 136–137). Second, the specific column for an ancient society in book two vanishes when that empire falls. By the time of Christ’s advent, only two societies are still recorded, the Jews and the Romans, the former vanishing from the work after the destruction of the Jerusalem temple in 70 CE. Thus, the Roman society is the only one which continues to Eusebius’ time, leaving the impression that ‘what occurred within the Empire during the lifetime of Eusebius was of world-historical significance’ (Johnson 2014: 88; see also Rosenberg and Grafton 2010: 15).
Eusebius’ historical works, which remain foundational for understanding the historical activity of the church in its first three centuries, have undergone harsh scrutiny during the last several centuries by historians for his selective and often uncritical use of evidence. Thus, Jacob Burckhardt, for example, famously calls Eusebius ‘the first thoroughly dishonest and unfair historian of ancient times’ (Burckhardt 1880: 334) and Walter Bauer wonders if any truth can be gleaned from some of his accounts (Bauer 1934: 9). In response, some scholars in the late twentieth century, such as Arnaldo Momigliano, T. D. Barnes, and Averil Cameron have defended his historical works, arguing that Eusebius should not be subjected to the critiques of modern historical methods – in fact, he ‘rethinks history’ in the wake of the shocking reality that Rome had a Christian emperor just years after the Diocletian persecution (Momigliano 1963; Barnes 1981; Cameron 1983). Recently, scholars have focused on Eusebius’ rhetorical constructions in the Ecclesiastical History. For instance, James Corke-Webster has argued Eusebius frames the church to meet the needs of an evolving Roman Empire in this work: ‘Eusebius’ History […] is a dramatic attempt to create a new vision of Christianity, in a new form, for a new world’ (Corke-Webster 2019: 84). Additionally, research on Eusebius’ Chronicle has focused on its innovative employment of emergent technology in the ancient world (Coogan 2022: 54–56; Riggsby 2023), which created ‘new possibilities of historical and textual knowledge’ (Coogan 2023: 68).
It is important to note that Eusebius’ goal in producing these works is not only historical but theological and apologetic (categories that are not separate in his mind) – he presented history as a unified narrative of God’s purpose for humanity. As Thomas O’Loughlin argues, the Ecclesiastical History is ‘more akin to a narrative theology’, such as Augustine’s City of God, and thus ‘we should investigate authors like Eusebius primarily as theologians rather than assess them in terms of their use of an “historical method”’ (O'Loughlin 2009: 92). For Eusebius, this theological vision included the progression of history from Abraham to Christ and finally to Constantine, where the Roman Empire fulfilled divine peace. Eusebius then employs this theological understanding in an apologetic way throughout these works, defending the antiquity of Christianity amidst accusations of novelty and assigning the success of the Roman Empire to the incarnation (Droge 1992; Burgess and Kulikowski 2013: 124–125).
As with many of Eusebius’ other writings, the composition of these works is pedagogically useful. In Ecclesiastical History, for instance, lengthy quotations make obscure historical writings accessible for a person without a large library. So, too, the technological innovation of the Chronicle ‘created a new kind of physical object and devised new conventions for organizing information for storage and retrieval’ (Grafton and Williams 2006: 135), and opened up new avenues of Christian scholarship. As Jeremiah Coogan argues, the Chronicle ‘is a form of open data: Eusebius constructed a database to organize his research and made this available to subsequent readers’ (2023: 69). Eusebius not only christianized history – he made that history available to the Christian world.
5.1.1 Legacy
Eusebius’ theological vision of history became the dominant view throughout the Christian world. His Chronicle, for instance, has been deemed ‘one of the most influential books of all time’ by Brian Croke. Croke continues: ‘As such it was continually copied, adapted, translated and continued from the earliest and its span and annalistic layout became the pattern for chronicle writing in the Middle Ages in both the Greek East and Latin West’ (Croke 1982: 195). His influence is not limited to the Greek and Latin world, though – every subsequent Christian chronicle across traditions in Syria and Armenia, indeed all chronicles in ‘Oriental, Slavic and Celtic languages’ can be traced back to Eusebius (Croke 1982: 195; Adler 1992; Drost-Abgaryan 2016). Further, influential writers such as Augustine, Cassiodorus, and Isidore of Seville make use of Eusebius’ Chronicle (as translated and expanded by Jerome) in their own historical accounts.
The Ecclesiastical History, likewise, became the foundation for all other narratives of ecclesiastical history in this period. Michael Hollerich notes that it was quickly translated into Latin, Syriac, Armenian, and potentially Coptic, thus becoming the dominant interpretation ‘of early Christianity in both Eastern and Western Christianity for centuries to come’ (Hollerich 2021: 47). The work was held in such high regard that later authors such as Rufinus of Aquileia, Socrates of Constantinople, and others simply added their material to his account in their own church histories.
5.2 Biblical scholarship
While Eusebius largely developed the discipline of ecclesiastical history, Christian intellectuals had long practiced biblical scholarship. This is most evident in the Hexapla, a critical edition of the Hebrew Bible developed by Origen of Alexandria in the third century. This work contained six columns: the original Hebrew in one column, the transliterated Hebrew into Greek in the next, and four (though occasionally more) Greek translations in the subsequent columns (for background and bibliography, see Meade 2024a). Eusebius builds on the work of Origen and the Hexapla in particular, which he claims is in his possession in Caesarea (HE 6.16.3). This is further evidenced by his frequent reference to the Hebrew and comparison between Greek translations included in this work (e.g. DE 8.2.12, 10.5.2; Commentary on Isaiah 2:7), suggesting he is using the Hexapla in his own exegesis and interpretation (Meade 2024b: 159–168). Eusebius’ original contributions to biblical scholarship also mark an important shift in conceptions of the biblical text, especially through his innovative study tools.
Eusebius wrote several commentaries on biblical books – the Commentary on Isaiah (after 325), the massive Commentary on the Psalms (after 326), and (now fragmentary) commentaries on Luke, Daniel, and 1 Corinthians. Throughout, Eusebius employs both allegorical and literal exegesis, even if he seems to place a larger emphasis on the latter in the last decade of his life (see Young 1983: 21–22; Hollerich 1999: 67–102; Zamagni 2011). In the preface of his Commentary on Isaiah, Eusebius clarifies when one must employ literal and allegorical exegesis:
At times the Spirit delivered his revelation to the prophet plainly, so that there was no need of allegory to explain the message […]. But at other times, the Spirit communicated through symbols and circumstances […] weaving together a literal and a metaphorical sense. (Commentary on Isaiah, preface)
Broadly, Eusebius usually restricts allegory to opaque passages or literary forms that might demand it.
An important focus of Eusebius’ exegesis is interpreting prophecy. Eusebius often begins by examining the literal fulfilment of a prophecy in the Old or the New Testament, with special emphasis on their realization in Christ (e.g. Commentary on Isaiah 3:9–15, 51:4–5; Commentary on the Psalms 88:11). Eusebius, then, sometimes employs ‘spiritual’ or ‘allegorical’ exegesis in a prophetic passage, uncovering the ‘inner, religious, and supernatural dimension of historical events’ to reveal ‘the meaning of a historical event in the overall design of God’s salvific plan’, as Hollerich (1999: 87) notes. While these spiritual meanings often point to the grand narrative of salvation history, Eusebius is also willing to apply these prophecies to the individual Christian (e.g. DE VII.1.49).
One aspect of Eusebius’ exegesis and scholarship that has received significant scholarly attention is his understanding of Judaism. Eusebius attaches different meaning to the terms ‘Hebrew’ and ‘Jew’, arguing the former is an ancient title applying to people of faith before Moses, while the latter refers (mostly negatively) to followers of the Mosaic Law and those who eventually rejected Christ (e.g. PE 7.6, DE 1.2.2; Johnson 2006: 94–125). However, Jörg Ulrich has highlighted how these terms are employed loosely by Eusebius and cannot be strictly understood as a chronological progression from one to the other (Ulrich 1998: 57–131). While Jews came after the Hebrews at the institution of the Mosaic Law, Eusebius mentions ‘Hebrew’ figures after Moses: Isaiah, Jeremiah, David, and contemporary figures such as Philo and Josephus are identified as ‘Hebrews’ (DE 1.4.7, 1.4.5, 4.15.34; HE 1.5.3, 2.4.2–3). ‘Hebrews’, then, are not only defined by time in Eusebius’ thought, but by the extent to which they are loyal to God and are morally opposed to polytheism (Ulrich 1998: 68).
This distinction between ‘Jew’ and ‘Hebrew’ is employed by Eusebius in several ways. First, it is used to explain in what ways the Hebrews and Jews were chosen by God and to justify the Christian use of the Jewish scriptures while rejecting the law (DE 1.1; Hollerich 1999: 119; Chazan 2016: 53–57). Second, he uses this distinction in apologetic arguments, demonstrating the antiquity of the Christian faith (Iricinschi 2011: 85). Not only is Christianity established prior to ‘Hellenism’ but it is also older than Judaism, as it is derived from the Hebrews (DE 1.2.10). Further, his apologetic works also respond to questions and criticisms raised by Jews (PE 1.1; Kofsky 2000: 89). Third, this distinction allowed Eusebius to shape both Christian and Jewish identity: the history of Israel is now framed as one of deviation and fidelity to Christian truth, one in which Christians are the true inheritors of the Hebrews. This point has been explored in creative ways: Andrew Jacobs has discussed how Eusebius’ Onomasticon (see below) ‘absorbs the holy land Jews into a facet of Christian identity’ (Jacobs 2003: 36), and Sabrina Inowlocki has investigated how Eusebius’ citations of Jewish authors make them ‘appear as the spokesmen of Christianity’ (Inowlocki 2006: 289–290).
Moving beyond his commentaries and some of the exegetical strategies employed therein, Eusebius also composed works to instruct readers on how to interpret the Bible, including General Elementary Introduction and Gospel Questions and Solutions (GQS; 313–317). Aaron Johnson states the former is an ‘introductory manual for the student of the Scriptures’, including training on the historical books of the Hebrew Bible, Psalms, wisdom literature, and prophets (Johnson 2011: 100). The latter is ‘a sort of compendium of exegesis concerning different controversial passages of the Gospels’, in which Eusebius discusses several difficult pericopes in the gospel narratives which seem to be at odds with one another – particularly the genealogies and the resurrection accounts (e.g. GQS ad Stephanum 4–5; GQS ad Marinum 1–4; Zamagni 2013: 207). These texts assist in how the scriptures should be read, overcoming any critique or potential discrepancy the reader may identify in their study of the Bible.
Further, Eusebius enables his readers to interpret the biblical text on their own through his development of innovative study tools, including the Onomasticon (324), Psalm Tables, and Canon Tables (303). The Onomasticon lists the place names referenced in the scriptures and notes their location according to contemporary sites. Thus, one is able to connect the events of the biblical narrative with their geographical location under the Roman Empire, bringing ‘biblical, Roman, and Christian realities together in such a way that Christianity in his own day can be seen to be the successor of the biblical realities of the Roman world’, as noted by Dennis Groh (1983: 29). The Psalm Tables, a work which has been tentatively ascribed to Eusebius (the sole surviving manuscript does not identify the author), sorted the psalms according to authorship (Wallraff 2013). Finally, Eusebius’ most famous tool is the Canon Tables, an inventive cross-referencing system which connects corresponding passages across the gospels (Nordenfalk 1938; Crawford 2019; Coogan 2022), which is indebted to earlier works in astronomy (Ptolemy, Handy Tables; Nordenfalk 1982: 33) and biblical scholarship (Crawford 2014).
Additionally, Eusebius is a vitally important figure in the formation and transmission of the biblical text itself. First, in Ecclesiastical History, he draws attention to other ecclesiastical writers’ thoughts about the scriptures: ‘But as the narrative proceeds, as I recount the successions I will mention at the appropriate times who among the ecclesiastical writers used any of the disputed writings, and what they say about the registered and acknowledged writings and about those that are not’ (HE 3.3.3). Eusebius then makes a list of books, sorting them according to his judgement concerning their canonicity: accepted, disputed, spurious, and rejected (HE 3.25.1–7). Eusebius is thus involved in the discussion of which texts should be recognized as scripture at an early stage. Second, Constantine requested fifty ‘copies of the divine scriptures’ from Eusebius in the 330s, giving him an opportunity to legitimize and distribute his version of the Bible, along with his Canon Tables (LC 4.36; for discussion about what these ‘copies’ might include, see Skeat 1999). Third, Eusebius allows for a new reading of the gospels through his Canon Tables, which demonstrates their theological unity. The most natural reading of each gospel is a linear one, but the Canon Tables allow for a nonnarrative reading of the texts where multiple corresponding passages can be read together. As Francis Watson notes, ‘[o]ne reads through the text, from the beginning toward the end, but one may also now read across the text, from one location to a second and perhaps also to a third and fourth’ (Watson 2016: 123, original emphasis; see Coogan 2017). By using the tables, readers are encouraged to read and study the gospels as corresponding and united works, which enforces a close relationship between the texts (Crawford 2019: 100–105). In sum, Eusebius’ relationship with the biblical text is not confined to commentary and instruction – he shapes the texts recognized as scripture and allows for a new type of reading therein.
5.2.1 Legacy
While Eusebius’ commentaries and exegetical themes are influential throughout the fourth century, it is his study tools that are his most important, as they revolutionized the way the scriptures were perceived and handled. And his work is certainly revered – a sixth-century Ethiopian manuscript, the Garima Gospel, depicts Eusebius as the fifth gospel writer for his Canon Tables (Coogan 2022: 1–4). This apparatus, which contained the tables and the introductory Letter to Carpianus, is found in over 1,000 extant manuscripts from the sixth to the twentieth century in Greek, Latin, Syriac, Gothic, Armenian, Georgian, Ethiopic, Coptic, Arabic, Slavonic, and others (Coogan 2022: 123–136), making it the most widely copied and translated nonbiblical text in late antiquity. The proliferation of the Canon Tables ultimately contributed to theological conceptions of scriptural and divine unity across the Christian world (see Crawford 2019).
6 A theology of the Son
In the early fourth century there was fierce debate over the begetting, nature, and characteristics of the Son of God, which produced foundational theological terms and categories for Christian conceptions of God. Naturally, this period and the ‘Arian’ controversy have received much scholarly attention, of which Eusebius is no exception. While it is important to position Eusebius’ theology amidst this controversy, it would be a mistake to reduce his theology to it: his entire corpus shows a consistent focus on the Son of God in particular, the centre of his intellectual framework. So, his Ecclesiastical History begins with the preexistence of the Son (HE I.2), the Demonstration of the Gospel prioritizes proofs of Christ divinity (e.g. DE 3.4, 9.12), and In Praise of Constantine frames the emperor as virtuous insofar as he participates in the Logos (LC 2.1–5). Eusebius’ discussion of the various loci of Christian doctrine – soteriology, cosmology, eschatology, etc. – all hinge upon his theology of the Son.
6.1 Relationship to the theology of Arius and the Council of Nicaea
Eusebius’ contributions to trinitarian and christological theology in the Arian controversy and the fourth century have not always been appreciated. Most scholarly surveys of this debate in the twentieth century assert that Eusebius is inconsequential to the development of doctrine (Grillmeier 1975: 177) or frame his role as a minor character who opposes Nicaea (Hanson 1988: 59; Behr 2004: I.158). More recently, scholarship has assigned Eusebius a more central theological role in the controversy and its reception, though with radically different conceptions of what that might be. On the one hand, Holger Strutwolf (1999), Christopher Beeley (2008a; 2012: 49–104), Aaron Johnson (2014: 113–142), Mark DelCogliano (2006), Brian Daley (2018: 102, 106–115), and Adam Renberg (2021; 2023) have largely sought to distance Eusebius from Arius’ own theology and demonstrate his impact on the later anti-Marcellan tradition that informed Cappadocian theology. On the other hand, Samuel Fernández has argued that Eusebius himself is the impetus for the Council of Nicaea, the true (though unnamed) opponent of Alexander of Alexandria and the leader of the alliance of which Arius is a part (Fernández 2025: 63–122). In both cases, Eusebius is now viewed as central to the Arian controversy and the development of doctrine, either in continuity or reaction to his thought.
To discuss his theological relationship to Arius and the Council of Nicaea demands an understanding of both Arius’ theology and the council’s – both areas of lively debate amongst scholars. If this is a debate strictly concerned with the eternal generation of the Son (Fernández 2025: 224), Eusebius seems to be quite close to Arius’ theology, insofar as he identifies eternality with the Father and prioritizes the dependence of the Son in his generation (e.g. DE 4.3.5; Ecclesiastical Theology [ET] 2.23.1–2). If the debate concerns the full divinity of the Son and his likeness to the Father, Eusebius seems closer to Alexander (Strutwolf 1999: 25–26) in prioritizing the exact likeness between the two and affirming the Son’s divine attributes (e.g. DE 4.3.10, 5.41.12). Finally, if the theology of Nicaea is most aligned with the theology of Eustathius and Marcellus, there is no doubt that Eusebius is at odds with the council, as he condemns both as heretical (Socrates, Ecclesiastical History [HE] 1.23.8–24.9; Against Marcellus [CM] 2.4.29–31). But, if Nicaea bears more resemblance to the theology of Alexander and Athanasius, Eusebius might be more easily aligned with the council (for discussion, see Parvis 2006: 38–95; Hanson 1988: 175–177).
While scholars might debate Eusebius’ theological relationship to Arius and Nicaea, his own discussion is more straightforward: he frames himself as ‘Nicene’, insofar as he signs the creed and champions the council in a later work. He discusses the purpose and theology of Nicaea in several places. First, amidst his discussion of the council in Life of Constantine (VC 3.4–24), Eusebius prioritizes ecclesiastical unity rather than the triumph of a particular theology, the common faith of the church in overcoming theological divisions and common worship in the newly set date of Easter (see Johnson 2021). Second, he discusses how to understand the theology of Nicene Creed and its terminology after the council in the Letter to his Diocese (325). After recounting the Nicene Creed, he examined ‘in what sense they say “from the ousia [being] of the Father” and “homoousios [consubstantial] with the Father”’ (FNS 37.9). According to Eusebius, after these terms and phrases were explicated in a satisfying way, he accepted them, as the explanation was ‘in conformity with what we ourselves confessed in the faith we had already presented’ (FNS 37.17).
So, why did Eusebius feel compelled to discuss these phrases and terms? Perhaps it was because the theology espoused at Nicaea was at odds with Eusebius’ own, so he was attempting to make it more palatable for his congregation (Behr 2004: I.153–161). Or perhaps it was because the now famous term ‘homoousios’ (consubstantial) had materialistic overtones in this period and was not yet integral to anyone’s theological system (Vaggione 2000: 56; Edwards 2021: 145–149). Regardless, Eusebius shows a desire in the letter to avoid any material division in God and the claim the Son is a part or accident of the Father (FNS 37.12), in addition to his affirmation of the unique generation of the Son from the Father (FNS 37.13). As his described definition of homoousios accomplished these ends, he was comfortable with the term (Ayres 2004: 351).
Importantly, his definition and recollection of the discussion of the creed varies from Athanasius’ account several decades later (Athanasius, On the Council of Nicaea 1–5, 19–24). Further, according to the later church historian Socrates, he was dragged into a pamphlet war with Eustathius of Antioch over the interpretation of the Nicene Creed and trinitarian doctrine after the council: ‘Eustathius, bishop of Antioch, accuses Eusebius Pamphilus of perverting the Nicene Creed; but Eusebius again denies that he is transgressing the creed of Nicaea, and pushes back’ (Socrates, HE 1.23.8–24.9). In other words, while Eusebius might have had legitimate reasons to interpret the creed in certain ways, Eustathius at the very least saw this as a perversion of its meaning.
6.2 Trinitarian theology
If one takes Eusebius’ pre-Nicene letters as representative of his theology (FNS 12–14), his position seems to resemble that of Arius and Asterius of Cappadocia, a key theologian who supported Arius. But, if one surveys his entire corpus, especially Demonstration of the Gospel (313–317), and two late works, Against Marcellus (337) and Ecclesiastical Theology (337), his statements are nuanced considerably. In these works, Eusebius demonstrates a robust trinitarian theology that not only combats what he conceives as Sabellianism, a trinitarian theology which denies distinct persons in the Godhead, but also subtly critiques Arius’ position.
Demonstration of the Gospel is primarily an apologetic work, even though it discusses important theological doctrines. Where the Preparation is primarily concerned with philosophy and ‘recent converts from among the heathen’, the Demonstration is chiefly devoted to the scriptures and ‘the proofs of God’s mysterious dispensation in regard to our Lord and Saviour Jesus Christ’ (PE 1.1). The focus in the Demonstration is on the superiority of Christian scriptural interpretation over Jewish exegesis, the fulfilment of Old Testament prophecies in Christ, and specific theological questions about Christ’s humanity and divinity. Against Marcellus and Ecclesiastical Theology are both polemical works written against Marcellus of Ancyra, a fierce theological opponent of supporters of Arius, in the late 330s. The former was written in the wake of a council in Constantinople in 336 to explain the condemnation of Marcellus, pointing out his divisive behaviour and theological errors without a full-scale refutation. Ecclesiastical Theology was meant to provide a more systematic and comprehensive critique of Marcellan theology. While these polemical works are meant to condemn Marcellus, there is much constructive theology therein which elucidates Eusebius’ own theological system.
Throughout his theological works, the starting place of Eusebius’ trinitarian theology is the Father, especially his unbegottenness or aseity. As the uncaused being, he is the one who has life in himself – thus, he is God. The Father is ‘the one and only God, the only one without source and unbegotten, the one who possesses the divinity as his own’ (ET 1.11.1). For Eusebius, source language is especially important, both in defining the divinity of the Father (that is, without source), and the reliance of all else on the Father for existence as their source.
If the Father is the ‘first God’, insofar as he is the unbegotten, the Son is the ‘second’: For the One [Father] gives, and the Other [the Son] receives; so that strictly the first is to be reckoned God alone being God by nature, and not receiving [divinity] from another. And the other is to be thought of as secondary, and as holding a Divinity in both being conceived of as one in type, God in Himself being one without beginning and unbegotten. (DE 5.4.14)
As the Father is the uncaused being, and thus the giver, he is God by nature. But the Son is begotten, thus receiving divinity from the first. Eusebius’ theology of the Son, then, is undoubtedly a subordinationist one. So, he writes in his early Letter to Euphration, ‘[f]or the Son of God himself, who quite clearly knows all things, knows that he is different from, less, and inferior to the Father’ (FNS 14). But what does he mean by ‘inferior’ or ‘second’?
Eusebius’ subordinationism has been viewed in two ways. On the one hand, some scholars have evaluated his theology according to its similarity to middle and neo-Platonic philosophy, especially that of Plutarch and Numenius, as discussed above (e.g. Ricken 1967). Therein, Eusebius’ subordinationism is often viewed as an ontological one, akin to Arius, who seems to deny certain divine attributes of the Son and allows for the creation of the Son from nothing (even if his creation is unique from other creatures; FNS 11). On the other hand, some scholars have noted Eusebius’ language about the second person of the Trinity most frequently employs the logic of the scriptural title ‘Son’, which naturally leads to a derivational type of relationship – the Son comes from the Father (Simonetti 1975: 63; see Sonship in the Bible). Eusebius’ employment of this title, in juxtaposition to Arius, firmly establishes the exact likeness of the Father to the Son and his unique generation from the Father (as opposed to creation out of nothing) (DE 5.4.10; ET 1.10.1). In other words, while there is a similar emphasis in Arius’ and Eusebius’ priority of the Father over the Son, the Caesarean does not seem to argue for an ontological inferiority in the Son, but a logical inferiority in being Son. Not only does this distinguish Eusebius’ subordinationism from other forms which are more extreme (such as Arius’ or Asterius’), but it shows certain affinities to Alexander of Alexandria and later homoiousian positions. To mark out the similarity and difference from other contemporaneous forms of subordinationism, this author has suggested the modifier ‘derivative subordinationism’ to mark out what both distinguishes and secures the divinity of the Son for Eusebius: his derivation of the Father (Renberg 2021: 58).
The logic of ‘sonship’ is used in four ways throughout Eusebius’ corpus. First, he uses it to distinguish between the persons in the Godhead, especially in his debate with Marcellus. Marcellus espoused a theology that emphasized the unity in God to such an extent that Eusebius feared it was Sabellianism repackaged, especially as it rejected distinct hypostases (persons or subsistences) in the Godhead (e.g. ET 2.5; Marcellus, Frag. 67, 87). Eusebius, conversely, argued the respective titles of Father and Son demonstrated their differences: the church must
name neither the Son Father nor the Father Son, but to worship on the one hand the Father who is ingenerate […] but on the other to believe that [the Son] has been begotten by the Father and subsists. (CM 1.1.17–18)
The titles of Father and Son are key here – they demonstrate both the unique hypostases of the two as well as their natural relationship, shaping their respective identities: ‘For of whom will [the Father] be Father, if no Son subsists’ (ET 1.4.1)? In other words, the personal relationship between Father and Son marks out their unique existence.
Second, sonship secures the divinity of the second person of the Trinity: ‘And the general cause also of His being God, would be the fact that He alone is Son of God by nature, and is called Only-begotten’ (DE 5.4.12). While he is not God by nature – a title Eusebius reserves for the Father – he is the Son of God by nature, and thus divine. In his Ecclesiastical Theology, he writes: the church ‘proclaims the Son of God to be God and Lord and teaches that he is truly Son and God’, learning to worship him ‘as Lord and Savior and its God’ (ET 1.10.5). As he is the Son of God, he must be God himself.
Third, Eusebius uses sonship to argue for an exact likeness between the Father and Son:
For what variation could there be from this complete likeness to the Father, except one that was a declension and an inferiority; a supposition that we must not admit into our theology of the Son. (DE 4.3.10)
Throughout his corpus, Eusebius predicates every characteristic of divinity to the Son, barring unbegottenness. He distances himself from Arius here, who seems to claim the Son does not have full knowledge of the Father (FNS 18). Eusebius, from his earliest documents, argues the Son knows all things, including the Father, on account of his relationship to unbegotten one (e.g. ET 1.13.2; CM 1.1.21).
Fourth, Eusebius employs sonship to distinguish between the way the Son comes from the Father and the way creation comes from the Father. In his later works, he avoids ‘creation’ language for the Son, employing the language of begetting instead, to demonstrate the difference:
For what would an offspring of God who has been made like the one who has begotten him be [other than a true Son]? Therefore, on the one hand, a king creates but does not beget a city, while on the other, he is said to beget, but not create, a son. (ET 1.10.1)
While creation and the Son share a common dependence on the Father for existence, the Son relates to the Father in a unique way.
Finally, Eusebius seeks to preserve divine unity using this logic of derivation. Eusebius roots the oneness of God in the Father as the eternal source, rather than in a shared substance: ‘Whereas the Father is Father and Lord and God even of the Son. Wherefore a reverent theology in our opinion rightly recurs to one Source of being and to one God’ (DE 5.8.3). If the Unbegotten is the one God, it is his participation in and likeness to the Father that secures their unity.
So that a likeness is implied not only of the being of the first, but also one of numerical quantity, for one perfect Being comes of the one eternal light […] for the Son of a Father who is One must be also One. (DE 4.3.8–9)
The Son is exactly like the Father in all ways, which means he is also exactly like him in number – that is, one. In other words, the distinct persons in the Trinity ground their differences and their unity. In this sense, rather than a true unity, it is perhaps more accurate to speak of the unity of God as a continuum of divinity, as Kelley Spoerl (1997: 34–35) has pointed out. At this stage in the development of doctrine, the category of substance had yet to come to fruition – Eusebius’ complete reliance on the relations in the Godhead for divine distinctions and divine unity limits his ability to maintain both.
This theology of the Son places Eusebius’ trinitarian theology in a unique position amidst early fourth-century theologies. Against Marcellus (who rejected two hypostases or persons in the Godhead), Eusebius emphasizes the unique nature of the Son and the Father as that which distinguishes their respective natures. Against Arius, it is the unique nature of the Son from creation which pushes him to critique those who use his begotten nature to paint him as a creature:
For this reason, one might rightly censure those who have dared to represent him as a creature, which came into existence out of nothing, like the remaining creatures. For how will he still be Son? (ET 1.9.1)
In other words, his emphasis on sonship drives him to critique both Arianism and Marcellan Sabellianism, in a middle position. One must note, though, that Eusebius never critiques Arius by name nor writes a work against him; he is far more concerned with Marcellus than Arius.
While Eusebius’ theology of the Son avoids many of the pitfalls of Arius’, there are still some dogmatic problems with it. First, he is unwilling to straightforwardly describe the Son as eternal. For Eusebius, this title is synonymous with unbegotten, so it must be reserved for the Father – to claim two eternal beings risks asserting two divine sources (Anatolios 2011: 61). Because of this, he even states the ‘Father precedes the Son’ in ‘existence, inasmuch as He alone is unbegotten’ (DE 4.3.5). Interestingly, he still claims the Son is begotten ‘before the ages’ and always ‘coexists as Son’ (ET 1.8.2) with the Father, which means there is a lack of clarity on the eternality of the Son (cf. God and the Philosophy of Time). In any case, Eusebius is adamant to deny the Nicene anathema: the Son is ‘not at one time non-existent, and existent at another afterwards, but existent before eternal time, and pre-existent, and ever with the Father as His Son, and yet not Unbegotten’ (DE 4.3.13; see FNS 32.4). Second, he argues the Son is ‘constituted’ as God by the Father (DE 5.4.10). While later writers are willing to describe the Father as the source of the Son, they do this with a qualification – sonship is assigned to the personal (hypostatic) relations with the Father, not his divine essence. While Eusebius employs many theological categories to protect the Son’s divine nature, he is limited in his ability to uphold his divinity because the Son is not only made Son but made God (Renberg 2021: 58–60). By the late fourth century, this aspect of Eusebian theology was eclipsed by the pro-Nicenes.
6.3 Christology: a theology of mediation
Throughout his corpus, Eusebius emphasizes the stark contrast between the creator, the Father, and his creation. So, the Father ‘is an Essence beyond and above all’ (Theophany 1.5), while creation is ‘not capable of drawing near to God’, because of its createdness (ET 1.13.1–4). Because of this, there can be no direct relationship between the two, which he describes vividly in a metaphor of the sun meeting the earth: ‘Suppose […] that the sun all-glowing came down from heaven and lived among men, it would be impossible for anything on earth to remain undestroyed’ (DE 4.6.4–6). In other words, the Father and creation are of two ontologically distinct types which are incompatible and unable to commune with one another. So how do they meet? The Logos.
On account of this cosmological framework, Eusebius’ theology emphasizes the role of the Son in creation as a mediator of the Father’s will and purpose. One of the main ways he discusses this is through the Son’s title as the ‘image of the invisible God’ (Col 1:15). This not only demonstrates the exact likeness of the Father and Son (DE 5.4.10) but also expresses how creation comes to see God through the second person of the Trinity. He continues the sun metaphor by describing the Logos as the sun’s rays, allowing for a connection between the sun and the Earth. Creation, thus, ‘might behold the flashings of the sun falling quietly and gently on them’ (DE 4.6.3). The Son of God allows creation to see and know the Father as if they are viewing a portrait or statue of a king (ET 1.20.73).
This cosmology also translates to Eusebius’ soteriology, which prioritizes the salvific role of the Son as teacher. As humanity is unable to know God the Father on account of their respective natures as mutable and immutable, they are largely ignorant of the true God and thus fall into idolatry. ‘They were not able with their mind to see the invisible, nor to ascend so high through their own weakness’, so they ‘worship things seen in the heavens, the sun and moon and stars’ (DE 4.8.1). While this is on account of humanity’s own free will, Lucifer and his demons feature largely here, as argued by Hazel Johannessen (2016: 99–138), deceiving humans in their ignorance. In sum, the fundamental problem of humanity is their ignorance of God, which leads to sin and vice. As Johnson notes, ‘the soteriological problem was also an epistemological problem: humans needed the image of God in order to see and know God’ (Johnson 2014: 129).
For Eusebius, the Son’s unique nature as the image of God means he is the only one who can make God known – he is ‘the ‘teacher of true knowledge of God’ (DE 1.1.2). This knowledge releases humanity from ‘all kinds of sin and diseases and troubles of the soul’, leading ‘countless hosts to the knowledge of the one true God, and to a healthy and pure life’ (DE 9.13.9). An interesting feature of this soteriology is its cosmic vision; this salvation is extended from all time. Salvation is not the work of the incarnation alone, even if it is fully realized in the economic work of Christ (Renberg 2021: 107–144).
Eusebius emphasizes several key ideas in his theology of the incarnation. First, Eusebius focuses on the continuity between the preexistent Son of God and the enfleshed Son of Man – God truly became human and experiences a human life. The continuity is especially apparent in his debate with Marcellus. As mentioned, Marcellus is hesitant to assign any titles other than ‘Word’ to the second person of the Trinity, including Son, as this might signal a distinction in the Monad. Thus, every christological title is assigned to the incarnation for Marcellus (Marcellus, Frag. 3, 7). Eusebius, conversely, argues that the titles of the Son – God, Only-Begotten, Image of the Invisible God – are true of both the preincarnate and incarnate Word (ET 1.20). Further, Eusebius accuses Marcellus of several christological heresies for denying the eternal personal relations in the Godhead, namely that the Father becomes incarnate and suffers (patripassianism) and that Christ is a ‘mere man’ (a teaching polemically ascribed to Paul of Samosata in the aftermath of the Council of Antioch in 268). The second person of the Trinity must truly take on a human nature in the incarnation to avoid these heresies. Second, for Eusebius the obedience of the Son in the economy is a continuation of his preincarnate obedience – he obeys the Father from all time (Commentary on Isaiah 2.37). Thus, biblical passages such as John 5:19 are straightforwardly read according to the hypostasis of the Son in relationship to the Father, rather than Christ’s humanity (ET 3.3.54–5).
The second key idea is concerned with the divine impassibility of the Son, maintaining his unchanging nature amidst the human experiences of Christ. In the incarnation, the Son is not ‘subject to similar passions [as the rest of humanity], nor was He bound to His body after the fashion of a human soul’ (LC 14.4). In other words, the eternal Son of God is not mutable nor is he restricted by the body – the human experiences of Christ do not indicate a change in the Son of God. This sometimes leaves the impression of an uneven Christology, which prioritizes the divine over the human, as he often discusses impassibility rather than human change in Christ.
While Eusebius’ focus is certainly on the divine in Christ, one must not overlook the ways in which Eusebius upholds his humanity, especially in scriptural passages that demonstrate a bodily weakness, such as hunger or thirst. He provides a hermeneutic for reading these passages, sometimes called ‘partitive exegesis’ (Behr 2004: I.14; Renberg 2025):
So that everything that follows, which may seem to lower His glory, must be taken as conceived of the Lamb of God that takes away the sin of the world, and of His human body. (DE 10.proem.4)
Every passage which seems to imply weakness in Christ must be predicated to the human, not the divine. Consequently, these pericopes are important for dwelling on Jesus’ humanity in Eusebius (Strutwolf 1999: 312).
It is here that the human soul of Christ becomes especially relevant, the focus of scholarly attention on Eusebius’ theology of the incarnate Son. Many scholars have argued Eusebius either denies a human soul in Christ (Spoerl and Vinzent 2018: 181, note 114) or thinks it unimportant (Hanson 1988: 55; Fernández 2025: 247). This scholarly assumption also grounds Sophie Cartwright’s proposal that Eusebius is the unnamed opponent in Eustathius of Antioch’s Against the Arians and On the Soul, a work which critiques the soulless Christology of the Arians (Cartwright 2015: 62–65). There is a cryptic passage in Ecclesiastical Theology 1.20.41–42 which seems to imply a rejection of Christ’s human soul by Eusebius, though Strutwolf (1999: 312–333) and Renberg (2021: 157–159) have argued this pericope should rather be read as a rejection of the teachings ascribed to Paul of Samosata, that Christ is a mere man. Eusebius affirms a human soul in Christ regularly elsewhere: the Son has a ‘human nature and a rational soul as other humans’ (Commentary on Isaiah 1.10).
In all of this, Eusebius affirms the single subjectivity of Christ, upholding his twofold existence as divine and human. As God, ‘[h]e continued to fill all things, and was with the Father’, even as ‘he lived as a man’ (DE 4.13.6). And as human, he endured birth and desired food: ‘If you marvel when you hear that God was born, you should believe also that he will yearn after food fit for an infant’ (Commentary on Isaiah 1.44). Thus, Eusebius held together two theological convictions that would become important in later christological debates, especially between Nestorius of Constantinople and Cyril of Alexandria in the early fifth century. He has a desire to protect the divine nature of the Son from change with the former and to uphold the single subjectivity of Christ with the latter. Christ is the divine Word himself, experiencing the incarnate life while remaining impassible.
6.4 Legacy
While his political, historical, and biblical scholarship mark an epochal change in perceptions of the world and the scriptures, Eusebius’ contributions to the development of doctrine are more modest – they mark an important step, but only a step. Many of Eusebius’ trinitarian and christological formulations were eclipsed by the late fourth century, particularly his derivative subordinationism. But this is not to say that his theology was uninfluential. Rather, his theological system paved the way for later important trinitarian formulations.
First, Eusebius was the most important transmitter of Origenian theology in the early fourth century, especially as Origen’s legacy was divisive even in this time. Eusebius employed Origen’s theological system to meet the demands of his ecclesiastical moment, while nuancing and jettisoning some of Origen’s controversial ideas. For later writers, in particular the Cappadocians, Origen was read through Eusebius. As Beeley notes for Gregory of Nazianzus, ‘[i]n this respect Gregory is far more a reformed Eusebian – or to be even more accurate, a vindicated Origenist – than he is representative of Athanasius and the West’ (Beeley 2008b: 316). The link between the two is made more probable when considering that Gregory resided in Caesarea Maritima in 347 and 348, and thus he might have encountered the works of Eusebius there (Gregory, Oration 7.6; McGuckin 2001: 37). Basil of Caesarea also seems indebted to Eusebius, both in theological categories and in exegesis. Mark DelCogliano (2008) has argued persuasively that Basil’s exegesis on Prov 8:22 (an important passage discussed amidst trinitarian debates in this period) follows Eusebius rather than Athanasius. Eastern theologians in the mid and late fourth century looked to Eusebius as an authority in Origenian theology.
Second, Eusebius is the progenitor of the anti-Marcellan tradition through his influential Against Marcellus and Ecclesiastical Theology. Figures such as Basil of Ancyra, Apollinarius of Laodicea, and Basil of Caesarea followed Eusebius in their attack of Marcellus of Ancyra and his student, Photinus, as the heretical counterpart to Arius (Lienhard 1999). Eusebius’ focus on the hypostases of the Father and Son in these works was the fullest theological reflection on the term up to this point, which aided in its importance in later works and trinitarian reflection. Further, Eusebius’ criticism of both Arius and Marcellus was the first to mark out the poles of trinitarian orthodoxy – a common rhetorical and theological move employed by the late fourth century (Spoerl 1997: 38). Through Eusebius, trinitarian debate necessarily focused on God’s personal relations – God must be known in himself and to the world as Father, Son, and Spirit.
