same time the empire had begun to make steps towards the recognition of the multiplicity of religions that it had come to encompass, but they came to an abrupt end with the Russian Revolution in 1917. After the revolution, the Russian Orthodox Church lost its privileges, as did all minority religions, and the new state verged towards an atheist official ideology. Under the Soviet Union, the Russian Orthodox Church lived periods of repression and periods of support and cooptation by the state. Despite the policies of state atheism, censuses reported a high religiosity among the population; in 1929, 80% of the population were believers, and in 1937 two-thirds described themselves as believers, of whom three-fourths as Orthodox Christians. The Russian Orthodox Church was supported under Joseph Stalin in the 1940s, after the Second World War, then heavily suppressed under Nikita Khrushchev in the 1960s, and then revived again by the 1980s. While it was legally reconstituted only in 1949, throughout the Soviet period the church functioned as an arm of the KGB; many hierarchs of the post-Soviet church were former KGB agents, as demonstrated by the opening of KGB archives in the 1990s. Since the collapse of the Soviet Union in 1987–1991, the Russian Orthodox Church has struggled to regain its erstwhile monopoly of religious life, despite it and other Christian churches which existed since before the Revolution have found themselves in a radically transformed context characterised by a religious pluralism unknown before 1917. During the Soviet period, religious barriers were shattered, as religions were no longer tied to ethnicity and family tradition, and an extensive displacement of peoples took place. This, together with the more recent swift ongoing development of communications, has resulted in an unprecedented mingling of different religious cultures. Study approaches In the study of religions in Russia, the "ethnic principle" is based on the assumption that the entire number of people belonging to a given ethnic group are adherents of that group's traditional religion. This principle is often used to estimate the magnitude of very small groups, for instance Finnish Lutheranism at 63,000, assuming that all the 34,000 Finns and 28,000 Estonians of Russia are believers in their historical religion; or German Lutheranism at 400,000, assuming that all Germans in Russia believe in their historical religion. However, whether for small or larger groups, this approach may lead to gross mistakes. The ethnic principle is sometimes misused