This chapter examines the religious Cold War, spawned by the West, and its impact throughout Europe. The religious Cold War was a diverse, multidimensional, complex global phenomenon whose salience varied according to the stage of the conflict, geographical location, cultural underpinnings, as well as national and local dynamics. Europe, where the Cold War began and ended, was a multiconfessional continent wherein Christianity, with its intimate historical, cultural, and indeed national links, was the dominant religion. The chapter focuses on the impact of the East–West power struggle on the churches and how they met its various challenges, especially fear of nuclear obliteration. During the Cold War religious organizations negotiated the arms race, détente, decolonization, globalization, secularization, and the growing importance of the developing world. The chapter examines their religio-political evolution as they encountered the Cold War, their contribution to ending it, and their position in the post-Cold War global order.