This article draws on a presentation at the annual symposium of the journal Sociologie, organized in collaboration with the Centre Emile Durkheim at the University of Bordeaux, May 25, 2012, on the subject "Sociology at its limits: Issues and Obstacles in Interdisciplinary Dialogue." We thank the article's author for having accepted our invitation to publish this text, very similar to his presentation, in our column "Critical Review." Published below, the text sheds light on the notion of religious belief as it is defined by sociologists, explaining current research programs in this research field (from a culturalist, economic or rationalist perspective) and highlights the interest for our discipline of a dialogue with historians, philosophers, anthropologists, linguists, psychologists and economists. The persistent question which justifies this multidisciplinary approach is to know what an individual says when he believes something, or when he says that he does not believe in it.