The Catacomb Church (Russian: ?) as a collective name labels those representatives of the Russian Orthodox clergy, laity, communities, monasteries, brotherhoods, etc., who for various reasons, have moved to an illegal position since the 1920s. In a narrow sense, the term "catacomb church" means not just illegal communities, but communities that rejected subordination to the Deputy Patriarchal Locum Tenens Metropolitan Sergius (Stragorodsky) after 1927, and adopted anti-Soviet positions. During the Cold War the ROCOR popularized the term in the latter sense, first within the Russian diaspora, and then in the USSR by sending illegal literature there. As a synonym for the "catacomb church" in this sense, the term True Orthodox Church (Russian: ?- ?, tr. istinno-pravoslavnaya tserkov) is also used,[by whom?] but as the historian Mikhail Shkarovsky notes: "the catacombness of the Church does not necessarily mean its intransigence. This term covers all unofficial and therefore not state-controlled church activities".
Organizationally, "catacomb" communities were usually not connected (organizations existed only in the NKVD cases). Accordingly, it is difficult to define the general ideology of the movement. In the underground were both communities that were quite loyal to the Moscow Patriarchate but did not have the opportunity to register and gather legally, and communities who believed that the power of the antichrist had come and that there could be no contact with the official church. Despite the absence of a common ideology and any organization, the Catacomb Church existed as a religious community and subculture.
The death of Patriarch Tikhon, the leader of the Russian Orthodox Church in April 1925 led to unrest among the followers of the church. Tikhon's designated successors were arrested by the civil authorities and Metropolitan Sergius was named "locum tenens," (that is, a cleric designated to substitute for another). Sergius issued a declaration in 1927 calling all members of the Russian Orthodox Church to profess loyalty towards the Soviet government. The declaration sparked division among the hierarchy, clergy, and laity, which led to the formation of the Russian True Orthodox Church, or Catacomb Church, a group of which was the Josephite movement.
Opposition to Sergius's declaration was based not only on his political concessions, but also on canonical and theological disagreements. His alliance with the authorities allowed him to turn over to the civil authorities all hierarchs (church administrators), and clergy who were at odds with him on both political and church-related issues.
Many church members and clerics were opposed to Sergius in church doctrine and backed the stand of the new True Orthodox Church. Most of them tried to observe Soviet law. Yet, the Soviet authorities had taken their stand in the dispute and were prepared to use whatever means necessary to bring the bishops under the control of their favorite, Sergius. This control by the Soviets caused True Orthodox Church eparchies (geographical areas under control of a bishop) and communities to go underground for the entire Soviet period.
In the 1970s and 1980s, many of these communities had lost their last bishops and many of their priests. They were forced to exist underground and celebrate services without a spiritual leader.