Can we—whether as individuals or as communities—break with our past? And if so, what force is required? The question is both an ancient and a very modern one, and it has often been imagined as a conflict between the power of the history we have been born into, and the possibility of conversion. Out of this debate there have emerged many discourses: discourses of genealogy, race, and historical determinism, and also discourses of grace, miracle, will, and interiority, among many others. This chapter suggests that how we have learned to think about the force of history—at least within the traditions of thought that have arisen within the reaches of Christianity, Islam, Judaism, and their attendant modernities—is itself intimately connected to how we have learned to think about the force necessary for conversion, and vice-versa. Drawing on the essays in this volume alongside writings ranging from scriptural sources to Søren Kierkegaard, William James, Friedrich Nietzsche, Franz Rosenzweig, Marshal Hodgson, and Michel Foucault, the chapter characterizes two aspects of how the force of history has been imagined in these traditions: the “Psycho-Social” and the “Kerygmatic.” It applies these forces to the case study of the massacre and mass conversions of Jews to Christianity in 1391, in order to demonstrate how the analytical tools with which many historians think about the past are themselves the product of thinking about conversion.