Catacomb Church
The Catacomb Church (Russian: Катакомбная церковь, romanized: Katakombnaya tserkov') 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 acting 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. The expression "True Orthodox church" (Russian: истинно-православная церковь, tr. istinno-pravoslavnaya tserkov) is synonym for this latter, narrower sense of "catacomb church".
The historian Mikhail Shkarovsky argues that "the catacombness of the Church does not necessarily mean its intransigence. This term covers all unofficial and therefore not state-controlled church activities".
Organizationally, the Catacomb Church communities were usually not interconnected.