Here is some information in a nutshell that explains how they “survived”… Even Stalin knew he needed that Church to help…
**For Bolsheviks who came to power in 1917 the Russian Orthodox Church was an ideological enemy a priori, as being an institutional part of tsarist Russia it resolutely defended the old regime also after the October revolution. This is why so many bishops, thousands of clergymen, monks and nuns as well as lay people were subjected to repression up to execution and murder striking in its brutality.
When in 1921-1922 the Soviet government demanded that church valuables be given in aid to the population starving because of the failure of crops in 1921, a fateful conflict erupted between the Church and the new authorities who decided to use this situation to demolish the Church to the end. By the beginning of World War II the church structure was almost completely destroyed throughout the country. There were only a few bishops who remained free and who could perform their duties. Some bishops managed to survive in remote parts or under the disguise of priests. Only a few hundred churches were opened for services throughout the Soviet Union. Most of the clergy were either imprisoned in concentration camps where many of them perished or hid in catacombs, while thousands of priests changed occupation.
The catastrophic course of combat in the beginning of World War II forced Stalin to mobilize all the national resources for defense, including the Russian Orthodox Church as the people’s moral force. Without delay churches were opened for services, and clergy including bishops were released from prisons. The Russian Church did not limit itself to giving spiritual and moral support to the motherland in danger. It also rendered material aid by providing funds for all kinds of things up to army uniform. Its greatest contribution, however, was expressed in financing the St. Dimitry Donskoy Tank Column and the St. Alexander Nevsky Squadron.
This process, which can be described as a rapprochement between Church and state in a “patriotic union”, culminated in Stalin’s receiving on September 4, 1943 Patriarchal Locum Tenens Metropolitan Sergiy Stragorodsky and Metropolitan Alexy Simansky and Nikolay Yarushevich.
Since that historic moment a “thaw” began in relations between church and state. The Church, however, remained always under state control and any attempts to spread its work outside its walls were met with a strong rebuff including administrative sanctions.
The Russian Orthodox Church was in a hard situation during the so called 'Khrushchev’s thaw" as well when thousands of churches throughout the Soviet Union were closed “for ideological reasons”.
The celebrations devoted to the Millennium of the Baptism of Russia, which acquired a national importance, gave a fresh impetus to church-state relations and compelled the powers that be to begin a dialogue with the Church, building these relations on the basis of recognition of the great historical role it had played in the fortunes of the Motherland and its contribution to the formation of the nation’s moral traditions.
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