Contrary to conventional readings of secularization and its usual analytical point of references – American and French civil religions, American religious vitalism and French laïcité – this article seeks to better understand an intermediary religio-political configuration, named ‘cultural religion’, as widespread as neglected. Independently from the question of faith, the full respect of religious practices or knowledge of dogma, Western populations maintain a cultural attachment towards Christianity, which may characterize one of the important contemporary social functions conferred to Christian churches, and help understand their deep cultural and historical impregnation. This article will address the conventional account of religious indicators, more precisely the religious type of ‘seasonal conformists’, the process of secularization as culturalization, and will distinguish between cultural religion, civil religion and political religion.