Constantinian political theology is back. Recent accounts of the transformation of the fourth-century empire have sought to write bishops back in as agents of change. Of course, the canonical accounts of Christian emperorship and the relationship between ‘church’ and ‘state’ written by episcopal theorists of empire never really went away. Yet attempts to compose a more realistic portrait of the period have tended to nudge the likes of Eusebius of Caesarea and Athanasius of Alexandria out of the foreground. In this book (a revised version of a 2021 UNC PhD thesis), Nathan Israel Smolin seeks to put Christian ‘political theorizing’ (2) back in the centre of the frame. ‘When 4th century bishops and Emperors alike wished to discuss the pressing questions of legitimacy, succession, hierarchy, equality, unity, diversity, and political power, they did so largely in and through Christian theology’ (2).

Ch. 1 sets out what S. sees as the stakes for Constantine’s self-presentation as a Christian emperor: his deficit of legitimacy as a ‘usurper’. ‘If Constantine was to rule stably, an alternative means would have to be found to sanction his authority in the eyes of subjects and potential rivals alike. (…) This method was religion.’ (15). S. traces the development of a Constantinian ‘imperial-episcopal judicial system’, from the Donatist appeal in 312 to Athanasius’ deposition in 336. He argues for Constantine’s increasing confidence in managing church councils and acting as the ultimate court of appeal for Christian disputes, as a plenipotentiary ‘servant of God’ (42). Ch. 2 then traces ‘the theology of Constantine’, arguing that we can discern the emperor’s distinctive interpretations regarding the debates of the 320s and 330s. S. seeks to delineate an evolving ‘imperial theology’ (44) — regarding Christology, politics, and both together — from his actions at Nicaea, letters to bishops in the following decade, and the Oration to the Assembly of the Saints.

Chs 3–6 follow these threads through Constantius II’s church politics and the responses of his episcopal critics. Ch. 3 suggests that the disorderly and divided succession undermined both Constantine’s political theology and his approach to ecclesiastical arbitration. The division of the empire prevented either Constantius or his brothers from providing final adjudication of disputes. Ch. 4 narrates the events of the 350s, as the empire returned to sole rule and Constantius used the precedent of his father’s role as ‘cosmic emperor’ to try proactively to bring about doctrinal unity. Chs 5–6 then consider how Lucifer of Calaris and Hilary of Poitiers responded to this perceived imperial over-reach, by articulating new political–theological schemas which denied the emperor’s privileged understanding of the divine will and subordinated him to, or excluded him from, the institutional church. An Epilogue traces the neo-Nicene development of factional organisation and conciliar self-help in the 360s and 370s absent such an overbearing imperial presence. It closes with Theodosius I and the promulgation of the Edict of Thessalonica, taken to confirm the retreat of the Constantinian emperor-as-theologian and to enshrine an episcopal monopoly on divine knowledge.

This book advances two attractive and convincing propositions: that we should take fourth-century emperors seriously as ‘theological interlocutors’ (3), and that ancient political theory shaped how contemporaries formulated and articulated their theological positions. It is less successful in standing up those propositions as part of a convincing account of fourth-century imperial and church politics. Partly, this is a problem of positioning; of pushing a case too far by trying to make one strand of political thinking into the key to Constantine and his successors once again. More fundamentally, it stems from a decision to limit the stakeholders in fourth-century political debate to emperors and bishops. If S. is able to make the 330s seem more like the 530s or 830s (compare 5), it is, in part, because the reduction of politics to negotiations between emperor and priests regarding their relative positions gives his account a certain timelessness. When we bring in the many other interest groups of imperial (or indeed church) politics, the difference in the practical significance of Christian political theology becomes pronounced. Crucial here is Noel Lenski’s demonstration of the modulation by Constantine’s regime of his self-presentation for different audiences (Constantine and the Cities, 2016). What changes over the fourth century is not so much the message — although, as S. traces, it clearly did change — but the context and frequency in which that message was articulated, and the assumed audiences. Reading the emperors solely through what they tell bishops will inevitably make political theology look (anachronistically) like their primary concern.

The choice to isolate the emperor likewise makes it difficult to assess his status as a ‘theological interlocutor’. In ch. 2, texts sent in Constantine’s name are taken to represent his own beliefs. But the emperor was a collective project. His pronouncements and decisions were shaped by, dictated to, and rhetorically zhuzhed up — sometimes even constructed whole cloth? — by his advisors, his petitioners, and wider groups of subjects. There is certainly a case to be made that statements of foundational personal piety reflect the personal role of the emperor in directing church politics. But this case is relegated to footnotes, and to arguments against the narrower contention that key texts were ghostwritten by the likes of Ossius of Cordoba. (Notably, the sections on Constantius II promote an equal and opposite assertion: that creeds explicitly written by bishops can be ascribed to the ‘authority’ of the emperor, e.g. 205). S.’s book rightly draws our attention to the sophisticated interventions of fourth-century imperial regimes in the content (and not simply the politics) of doctrinal controversy, and the development of ideas of the Christian emperor. To reassess their significance will require zooming out from these warring bishops to bring the rest of the fourth-century political landscape back into focus.