Anthropologists have moved away from using belief as the defining feature of religion, portraying it instead as something whose nature and significance vary among times and cultures. This raises new questions about how specific notions of belief come into being and their connections to social, cultural, and political systems. This article explores these questions in the Jewish community of Copenhagen, focusing on two periods when ideas about belief changed radically: the emancipation period at the opening of the nineteenth century, and the decades after World War II. In each, changes in the ways that Jews conceptualized and appealed to belief reflected changes in the internal social dynamics of Danish Jewry. They also reflected changes in the larger Danish culture and in state political agendas.