Religion in the Soviet Union

Religion in the Union of Soviet Socialist Republics (USSR) was dominated by the fact that it became the first state to have as one objective of its official ideology the elimination of existing religion, and the prevention of future implanting of religious belief, with the goal of establishing state atheism (gosateizm). However, the main religions of pre-revolutionary Russia persisted throughout the entire Soviet period and religion was never officially outlawed.

Source: Wikipedia — Religion in the Soviet Union (CC BY-SA 4.0)