[4] Unofficial Muslim, Catholic, Protestant, Judaic and Uniate groups in the Soviet Union also engaged in similar Catacomb-like activity.
Sergius issued a declaration in 1927 [ru] calling all members of the Russian Orthodox Church to profess loyalty towards the Soviet government.
[citation needed] The earliest documented use of the word "catacombs" to describe the Russian realities of the 20th century is found in the letters of abbess Athanasia (Gromeko) to Metropolitan Eulogius (Georgievsky), written in 1923 from Petrograd.
After the nuns were expelled from their church building by the Renovationists, the community did not disband, but continued its existence as a convent in a private home.
According to historian Alexey Beglov [ru], the term "catacombs" and its derivatives were a local Petrograd/Leningrad neologism, where there were many active church intellectuals who could appreciate the diversity of meanings associated with this word.
According to the ideologists of the ROCOR, the powerful underground church in the USSR which was in opposition to the Moscow Patriarchate proved the illegitimacy of the official hierarchy.
Archpriest Vasily Vinogradov [ru], who fled the USSR and served 6 years in Soviet camps, noted that Metropolitan Anastasius (Gribanovsky), who headed the ROCOR, and the hierarchs subordinated to him, wanted to live in a myth about the supposedly numerous catacomb Church that existed in Russia, and considered them as doing wishful thinking.
In response to her protests, the editorial board of Orthodox Russia replied: "The truth is extremely harmful for the cause of the church in America.
"[11] In 1974, Alexander Solzhenitsyn, who was exiled from the USSR, addressed an open letter to the participants of the 3rd All-Diaspora Council of the Russian Orthodox Church organised by the ROCOR, where, among other things, he criticized the "pious dream" of the existence of the "sinless – but also bodiless – catacomb" (о «сколь безгрешной, столь и бестелесной катакомбе»).
[14] In 1975, First Hierarch of ROCOR Metropolitan Philaret (Voznesensky) wrote to Solzhenitsyn that not only priests, but also bishops were part of the Catacomb Church.
After that, some authors in the USSR used the word "catacomb" to designate ecclesiastical opposition to the Moscow Patriarchate, while others used it as a technical term as a synonym for the epithet "illegal" from the point of view of Soviet legislation.