This book presents a new reading of the history of French social science and religion through an investigation of early sociology’s techniques for narrating the category of belief. The author argues that by looking at the history of social sciences in this manner, we gain a deeper understanding of both our present debates on post-secularity as well as our modernist past, both of which were thoroughly shaped by their reflections and critiques on the notion of belief yet failed to enter into any sort of meaningful communication with each other. This book seeks to rectify this failure by introducing the concept of ‘belief-languages’, an anthropological framework designed to historicize different discussions on belief and allow for their comparative description and analysis.