Apocalypticism has become an integral part of contemporary rhetoric surrounding the environmental crisis. Although the parallel with religious discourse is often drawn with the aim of discrediting ecological warnings, this work proposes to consider the comparison seriously in order to grasp its rationality. The Weberian category of “elective affinity”, often invoked to examine circulations between religious and secular spheres, is revisited here to explore convergences and discontinuities between religious apocalypticism and ecological catastrophism. Four aspects are examined: the relationship to time, the belonging to a specific “genre”, the ethos and the pragmatic aim. This work is based on a qualitative study of discourses on ecological “collapse” in France, Belgium, and Switzerland through 72 books, 11 videos published online, and 5 films and TV programs. It is complemented by the results of 15 interviews and 25 observations.