The book is devoted to the relationships between Nicene and Homoian Christianities in the context of broader religious and social changes in post-Roman societies from the end of the fourth to the seventh century. The main analytical and interpretative tools used in this study are religious conversion and ecclesiastical competition. It examines sources discussing Nicene–Homoian encounters in Vandal Africa, Gothic and Lombard Italy, Gaul, and Hispania – regions where the polities of the Goths, Suevi, Burgundians, and Franks emerged. It explores the extent to which these encounters were shaped by various religious policies and political decisions rooted in narratives of conversion and confessional rivalry. Through this analysis, the aim is to offer a nuanced interpretation of how Christians in the successor kingdoms handled religious dissent and how these actions manifested in social practices.

Chapter 9 focuses on the processes of transition from a state of schism to Christian unity in Gaul and Hispania. The comparison of two councils, that of Orléans in 511 and Épaone in 517, show the lack of a uniform pattern to the organisation and enforcement of this change. The second part of the chapter is devoted to the transformation of the Visigothic kingdom begun in 589 and interpreted as a huge project, developed in close collaboration between the king and the secular and ecclesiastical elites, which laid the foundation for Christian culture in seventh-century Hispania and demonstrated the transformative power of conversion ideas in the early medieval West.

This chapter examines the ways in which creeds have been collected in late sntiquity and in modern scholarship. Radde-Gallwitz first sketches the history of modern anthologies of creeds and argues that they have led to a conflation of distinct types of creeds, particularly in their portrait of a genealogical relation between creeds without anathemas and creeds containing anathemas. He argues that late-antique sources, by contrast, emphasise anathemas in their presentation of creeds. He examines sources such as canon collections and Athanasius’ De synodis and provides a new account of the afterlife of the anathema appended to the original Nicene Creed.

Historians today discuss the rules and regulations followed by medieval church courts by focusing on the development of so-called “Romano-canonical” procedure during the formative period of Roman and canon law from the time of Gratian (around 1140) to the completion, in the 1270s, of the most successful handbook on the subject, the Speculum iudiciale of William Durand. The guidelines laid down in the Speculum summarize more than a century of systematic effort at the schools of Bologna and elsewhere to strike a balance between, on the one hand, the obligation of judges to investigate the facts of a case unilaterally and, on the other, the right of defendants and adversaries to a fair trial. The specifics worked out by contemporaries have fascinated modern observers, not least for their innovative features. In twelfth- and thirteenth-century jurisprudence, demands of due process, the double jeopardy clause, presumption of innocence, and other fundamental standards of justice in the West found their first coherent expression. Simultaneously, though, research has operated under the erroneous assumption that manuals like the Speculum iudiciale were meant to cover the whole range of mechanisms shaping ecclesiastical adjudication.

The Eastern Roman Empire represents a prototype of a Christian state both in terms of its political philosophy of Church–state relations and in terms of a political philosophy regarding legal recognition of other states – both Christian and non-Christian. The process through which Byzantium recognized emerging states in Europe and beyond became an important element of international legal order as this dominant Christian empire addressed the most critical question of political legitimacy: how can a political order established by Christ recognize other political communities that challenge its territory? As a political community established by Christ and driven by the rule of law, the Empire navigated its international relations following a very specific theological program that reflected its attitude toward its neighbors. This program held that any political project should be an imitation of the Byzantine Christ-given political community and through such process it would come closer in affinity to the Empire and become integrated into its Christian commonwealth.

Constantine's role in calling the Council of Nicaea has long been recognized. But theological interests have overshadowed the political side of his decision-making. In the nineteenth century scholars coined the word “Caesaropapism” for imperial interference that they saw as a threat to the purity of the Church. But the ancient state operated on a different set of principles, and a political approach fills in important blanks in our understanding of the council. By the time Constantine took control of the eastern empire he had learned that the best way to deal with conflict in the Church was to assemble the largest number of bishops possible and have them settle the problem. This is the thinking behind his decision to ask all the bishops in the empire to settle the Arian question. This is why Nicaea became known as the first ecumenical (“world-wide”) council, though in reality almost all of the bishops present came from the East. Publicly, Constantine treated the bishops at Nicaea with respect and humility, but behind the scenes he worked to bring the opposing parties into agreement. The result was the Nicene Creed, still recited (in slightly different form) by Christians today.

This chapter narrates the emergence of the pro-Nicene alliance by arguing that it was a consensus-building movement. It begins by tracing the history of other consensus-building movements in the fractured theological landscape of the years 325-61 in order to demonstrate their development of various consensus-building tactics, which were ultimately used unsuccessfully. The impetus for the pro-Nicene alliance itself was dissatisfaction with, or the failure of, these previous efforts. Pro-Nicenes adopted four tactics of previous consensus-building efforts and deployed them successfully: (1) defining itself as the center between extreme positions, (2) promoting a minimalist creed that nonetheless ruled out extremes to be avoided, (3) acknowledging that the meaning of a creed was not self-evident and producing supplementary material to insure its correct interpretation, and (4) securing imperial patronage. The chapter then turns to shifts in thinking which occurred in the early 360s and made consensus between former opponents possible, taking Athanasius of Alexandria and Basil of Caesarea as paradigmatic examples of these shifts. The chapter concludes by narrating the consolidation and ascendency of the pro-Nicene alliance in the late 370s and early 380s.

The final chapter completes the analysis, weaving together themes from previous chapters to investigate how the canons were used. Beginning with the papal deployment of the conciliar authorities, the chapter suggests an inherent flexibility: while the papacy would reaffirm the conciliar decrees in some circumstances, in others it would use them merely as guidelines. The chapter then turns to local and episcopal use of the conciliar decrees, showing that in some cases bishops followed the stipulations, while elsewhere they attempted to avoid, change, or interpret them. Finally, the use of the decrees by canon lawyers, both in the schools and in episcopal retinues, is considered: immediately after the council, there was no one way in which these lawyers treated and understood the decrees, and it was only with Bernard of Pavia’s canonical collection known as the Breviarium Extravagantium (ca. 1191) that canon lawyers began to interpret them as overarching, general stipulations. Overall, the chapter points to the plurality of ways in which twelfth–century clerics conceived of papal and conciliar power and authority, with both conciliar decrees and papal decretals being viewed with uncertainty as they became established legal precedents.

This Conclusion reconsiders the aims of the book – to investigate how the ideas that underpinned the canons were drawn together, and then what happened to the canons after they left the conciliar environment – and draws larger conclusions on the ability and authority of the papacy to rule in the twelfth century, as well as commenting more particularly on the role that conciliar canons played as legal texts in the eyes of contemporaries. Using the conciliar canons, the innately responsive nature of papal government in all its forms can be deduced; most of the canons concerned issues of deep contemporary relevance that had been brought before the curia in the decade or so before the council, or were commented on in the schools. The chapter ends by suggesting that whatever the papacy’s intention for the conciliar canons, their ultimate effects and the continued resonance of their stipulations were the consequence of a prolonged dialogue between popes and local clerics.

This chapter first introduces the 1179 Lateran Council and then situates it within the broader history of the papacy and medieval canon law in the twelfth century. It begins by outlining the events leading up to the council and its emergence as the resolution to a damaging schism between Pope Alexander III and Frederick Barbarossa. The chapter then provides a brief, accessible account of twelfth-century canon law and its relationship to papal government. The role played by the papacy and by local clerics in creating contemporary canon law is analysed, and an overview of current ideas and thoughts provided, including an – of necessity brief – interlude into the debates surrounding the appearance of the Decretum Gratiani in ca. 1140. The aim is to situate canon law in the history of Church government in the central Middle Ages, before moving on to discuss the nature and purpose of church councils and the twelfth–century legal theories upon which their authority rested.

This chapter examines the West Frankish political controversies that defined Flodoard’s career and reassesses the nature of the historian’s involvement in them. Between 925 and 961, the see of Rheims was contested by two archbishops in a dispute that was intrinsically linked with wider political struggles in West Francia. Even though Flodoard tells us about his own participation in the archiepiscopal dispute, previous scholars have downplayed this involvement, considering it to have had little impact on his historical works. This chapter scrutinises Flodoard’s autobiographical remarks and portraits of the two rival archbishops, Hugh and Artold, arguing that his role in the dispute did have a significant bearing on the content and tone of his Annals and History of the Church of Rheims. The History, moreover, has tended to be viewed as a passive work of ‘local history’ primarily of benefit for the clergy of Rheims. Yet Flodoard composed it immediately following the resolution of the Rheims schism. By reappraising the nature of this settlement and Flodoard’s impetuses for writing, this chapter advances a broader interpretation of the purpose and audience of his History.