This book provides a new interpretation of the cristero war (1926–29), which divided Mexico's peasantry into rival camps loyal to the Catholic Church (cristero) or the Revolution (agrarista). It puts religion at the heart of our understanding of the revolt by showing how peasant allegiances often resulted from genuinely popular cultural and religious antagonisms. The book challenges the assumption that Mexican peasants in the 1920s shared religious outlooks and that their behaviour was mainly driven by political and material factors. Focusing on the state of Michoacán in western-central Mexico, it seeks to integrate both cultural and structural lines of inquiry. First charting the uneven character of Michoacán's historical formation in the late colonial period and the nineteenth century, the book shows how the emergence of distinct agrarian regimes and political cultures was later associated with varying popular responses to post-revolutionary state formation in the areas of educational and agrarian reform. At the same time, it is argued that these structural trends were accompanied by increasingly clear divergences in popular religious cultures, including lay attitudes to the clergy, patterns of religious devotion and deviancy, levels of sacramental participation, and commitment to militant ‘social’ Catholicism. As peasants in different communities developed distinct parish identities, so the institutional conflict between Church and state acquired diverse meanings and provoked violently contradictory popular responses. Thus the fires of revolt burned all the more fiercely because they inflamed a countryside that — then as now — was deeply divided in matters of faith.