Religion in Europe has been a major influence on today's society art, culture , philosophy and law . The largest religion in Europe for at least a millennium and a half has been Christianity . Three countries in Southeastern Europe have muslim majorities. Ancient European religions included veneration for dieties such as Zeus . Modern revival movements of these religions include Heathenism , Rodnovery , Romuva , Druidry , Wicca and others. Smaller religions include Indian religions , Judaism and some East Asian religions which are found in their largest groups in Britain , France and Kalmykia
Little is known about the prehistoric religion of Neolithic Europe . Bronze and Iron Age religion in Europe as elsewhere was predominantly polytheistic (Ancient Greek religion, Ancient Roman religion , Basque mythology , Finnish paganism , Celtic polytheism , Germanic paganism etc . ) The Roman Empire officially adopted Christianity in AD 380. During the Early Middle Ages most of Europe underwent Christianization, a process essentially complete with the Christianization of Scandinavia in the High Middle Ages . The emergence of the notion of "Europe" or "Western World" is intimately connected with the idea of "Christendom", especially since Christianity in the Middle East was marginalized by the rise of Islam from the 8th century, a constellation that led to the Crusades, which although unsuccessful militarily were an important step in the emergence of a religious identity of Europe. At all times, traditions of folk religion existed largely independent from official denomination or dogmatic theology.
The Great Schism of the 11th century and Reformation of the 16th century were to tear apart Christendom into hostile factions, and following the Age of Enlightenment of the 18th century , atheism and agnosticism have spread across Europe. 19th-century Orientalism contributed to a certain popularity of Buddhism and the 20th century brought increasing syncretism , New Age and various new religious movements divorcing spirituality from inherited traditions for many Europeans. The latest history brought increased secularisation and religious pluralism
