This book examines the religious and ideological consequences of mass conversion in Iberia, where Jews and Muslims were forcibly converted or expelled at the end of the XVth century and beginning of the XVIth, and in this way it explores the fraught relationship between origins and faith. It treats also of the consequences of coercion on intellectual debates and the production of knowledge, taking into account how integrating new converts from Judaism and Islam stimulated Christian scholars to confront the converts’ sacred texts and created a distinctive peninsular hermeneutics. The book thus assesses the importance of the “Converso problem” in issues such as religious dissidence, dissimulation, and doubt and skepticism while establishing the process by which religious dissidence came to be categorized as heresy and was identified with converts from Judaism and Islam even when Lutheranism was often in the background.