C. R. Galvão-Sobrinho examines how the Arian controversy shaped the episcopate during the fourth century. His book centres on the events of 318–362, describing the disagreements among bishops, the formation of alliances, the use of imperial support, the synods and councils aiming to depose some bishops and vindicate others, and the urban violence that broke out when the laity were called into action. Throughout his compelling narrative, G. makes his argument clear: the Arian controversy was the key factor that made bishops powerful public figures capable of instigating riots and opposing emperors. This new style of episcopal leadership, with its use of oppressive tactics against dissenters, was a departure from the approach of earlier Christian leaders, who sought to resolve differences within their communities through compromise. According to G.'s persuasive account, the turmoil associated with theological controversies did not stem from the rise of powerful bishops, but, rather, the controversies were what made the bishops powerful.

The book begins with an overview of bishops' responses to theological disputes in the third century (chs 1 and 2). Disagreements posed challenges to their claims to spiritual authority, but bishops negotiated with dissenters. G. emphasizes how rarely bishops were unseated for heresy: the appendix lists the few bishops investigated or deposed due to their doctrinal positions before the Arian controversy. Ch. 3 turns to the fourth century, when bishops became unwilling to compromise. The turning point was Bishop Alexander of Alexandria's formal condemnation of the priest Arius. Alexander's response to Arius’ views was normative and ‘left little room for negotiation and compromise with his opponents’ (42). In response, Arius hardened his stance and aimed to win his own supporters. Ch. 4 examines their attempts to woo the laity and how these interactions changed the nature of the episcopate. Support from the laity became ‘a source of both communal tension and personal strength’ (64).

In ch. 5, G. argues convincingly that Alexander's attempt to define orthodoxy for the entire Church and his attacks against fellow bishops were unprecedented: these actions eroded the culture of debate and compromise (72). The story continues in ch. 6, with the emperor Constantine becoming involved. Although he does not consider Constantine to have been the key factor in the shift from negotiation to confrontation, G. sees the emperor's criminalization of theological dissent as allowing episcopal authority to continue to develop on its trajectory, ‘solidifying that aggressive and performative style of church leadership that had emerged in the pre-Nicene years of the dispute’ (96).

Ch. 7 examines events from Nicaea to the death of Constantine: bishops deposed other bishops, deposed bishops refused to step down, bishops reached out to the laity, crowds rioted and Constantine tried to restore order by either deposing or reinstating controversial bishops. G. focuses on the growing power of the bishop, which can be seen in Alexander's seizure of churches (including their function as distribution centres for alms) from local priests, thereby channelling the laity's allegiance towards himself. G. makes a convincing argument that these actions led to ‘the crystallization of the monarchical episcopate’ (108).

The final chapter follows the controversy into the decades following the death of Constantine. G. notes two new developments: the ‘dramatic, unapologetic, and blatant use of compulsion’ and ‘violence as a legitimate means to engage in dispute’ (129). Bishops also rewarded their followers by establishing poorhouses. G. observes that ‘the founding of these institutions cannot be seen in isolation from the theological conflict and the bitter competition for the hearts and souls of ordinary Christians’ (149). G. concludes that the bishops’ power was neither inevitable nor caused by imperial support: rather, ‘theological disputes generated a pattern of action that pushed bishops to the center of public affairs’ (155). Imperial support merely enhanced their power. By 360, bishops had evolved into powerful social and political leaders, and both their violence and their popular outreach would continue in the following decades.

Throughout G.'s narrative, the emperors, including Constantine, play a supporting rôle, serving the bishops’ strategic interests. G. considers the growing intolerance of dissent and the use of violence in theological controversies to have been rooted in the actions of the pro-Nicene bishops of Alexandria, but not due to the involvement of emperors. G. rightly minimizes his discussion of theological arguments, which allows him to focus on the tactics used by the bishops to promote their views and authority. He makes a good case, however, that theological issues were not mere excuses for conflict. Moreover, the theological debates were not confined to the circles of church leaders: G. cites fascinating examples demonstrating how church leaders depended on their communities’ support and communicated with them through popular sermons, songs and pamphlets.

One unusual feature of this book is that the details relating to the chronology and other specific points are relegated to the appendix. As a result, the narrative keeps its momentum even up to the final paragraph. But, because of this structure, the book does not often engage explicitly with recent scholarship. More extensive discussion of how G. views recent work on episcopal authority and religious violence would have been a useful addition to the appendix. Future work on these topics will need to engage with G.'s arguments, because this book successfully makes the case that abstract ideas about God, bishops’ power struggles and the loyalties of laypeople could be factors that overshadowed emperors.