Secularization has been the subject of much debate during the 20th century. A first period, characterized by sociologists who sought strategies to resist secularization and dechristianization processes, was followed by a breaking away from the religious sphere: the sociology of religion was built around the dominant paradigm of secularization as a progressive loss of power for established religions. Since the end of the 20th century, however, analyzes have been more nuanced. Drawing on the European Values Study and the International Social Survey Programme, the second part of the article analyzes the different facets of religiosity (relationship to established religions, practices, religiosity, beliefs, and consequential dimension), which are not necessarily evolving in the same manner. Between secularity and religious beliefs, complex reconfigurations—often concerning possibility and uncertainty—are taking place, even though secularization corresponds to a particular value system that remains quite different from that of believers. This article seeks to better understand the secularization movement and the religious resistance.