The decline of religion refers to the gradual reduction in the influence and practice of organized religion in society, particularly noticeable in Europe from the mid-20th century onwards. This phenomenon is closely linked to modernization, secularization, and a growing emphasis on scientific rationalism, which together have led to a shift in cultural values and a re-evaluation of religious beliefs. The decline of religion played a significant role in shaping contemporary European identity and social structures during and after the Cold War era.