At the beginning of the 20th century the previously existing "symphonic" government-church relations were almost destroyed. The Church wanted more freedom from the government. The believers were also seeking for freedom of religious beliefs and freedom of conscience. The first steps in this direction were made by the interim government. It became clear that Russia was moving towards a secular state. Then the Soviet government made a drastic step in this direction. This book is about the development of the trend in 1917-53. The epoch of the "Stalin socialism" was a critical time for the fate of the Russian Orthodox Church. The author used many new sources on the subject.