The mainstream discourse in the sociology of religion has turned its back on the secularization thesis. Current approaches rather promote the idea of a revival of religion. Some of these approaches are based on definitions of religion that a-priori define religion as a necessary component of societies and thereby rule out the possibility of secularization processes. This rationale is already present in the theories of Thomas Luckmann and Niklas Luhmann. The architecture of their theories renders it impossible to describe changes in the vitality of religion. The objective of this article is to propose an alternative concept of secularization based on these two theories. In order to sensitize the two theories for potential changes in the vitality of religion, they are selectively combined with each other. The approach resulting from this combination indicates that religion competes today with a number of functional equivalents to religion for the treatment of “small- and middle-range contengencies”. Hence, secularization means for the Western European context that religion is losing ground in this competition and gets progressively substituted by non-religious functional equivalents.