Book excerpt: As the Roman Empire in the west crumbled over the course of the fifth century, new polities, ruled by 'barbarian' elites, arose in Gaul, Hispania, Italy, and Africa. This political order occurred in tandem with growing fissures within Christianity, as the faithful divided over two doctrines, Nicene and Homoian, that were a legacy of the fourth-century controversy over the nature of the Trinity. In this book, Marta Szada offers a new perspective on early medieval Christianity by exploring how interplays between religious diversity and politics shaped post-Roman Europe. Interrogating the ecclesiastical competition between Nicene and Homoian factions, she provides a nuanced interpretation of religious dissent and the actions of Christians in successor kingdoms as they manifested themselves in politics and social practices. Szada's study reveals the variety of approaches that can be applied to understanding the conflict and coexistence between Nicenes and Homoians, showing how religious divisions shaped early medieval Christian culture.