The main religions of pre-revolutionary Russia persisted throughout the entire Soviet period, but they were only tolerated within certain limits. Generally, this meant that believers were free to worship in private and in their respective religious buildings (churches, mosques, synagogues etc.), but public displays of religion outside of such designations were prohibited. In addition, religious institutions were not allowed to express their views in any type of mass media, and many religious buildings were demolished or used for other purposes.
Religion in the Soviet Union - Wikipedia