Modernity in the West had, among other things, the effect of encouraging people to distance themselves, especially from the more cultivated classes, from ecclesiastical structures, at first, and then from the Christian religion itself. This distancing had incidence on individualism, which also led to a modern vision of man and society. This paper discusses the main philosophical, political and cultural motives that directly influenced, especially after the French Revolution, the accelerated process of secularization. This process led to the skeptical and post-metaphysical attitude of the post-modernity of the 20th century. Unlike previous ones, it was a century in which atheism was not an attitude of few individuals among the intellectuals but it spread also to large groups of citizens. However, since the last two decades of the 20th century and the first decades of the 21st, some changes can be perceived that could indicate a return of interest towards religion in the West.