pg. 56 - Semyon Denisov, Pyotr Filippov
Two Russian monks and theologians, part of the Old Believers movement founded by Patriarch Nikon of Moscow. During the period of the founding of the movement, the Tsardom of Russia began secularizing; at the same time, rites from regional Orthodox churches (Greece, former-Byzantium) were slowly adopted in Russia. The Old Believers rejected said change, and were prosecuted by the Tsardom for it. Later, the Old Believers were revered as part of Russian literary tradition during the rule of the Russian Empire. (Howe, Jovan E. Traditional Culture and the Ritualists, 1998.)

pg. 57 - Nekrasov sect
A sect of Cossack Old Believers in the Donbass region, led by the Cossack commander Ignat Nekrasov. This sect fled towards the Caucasus (Kuzmin refers to the more-familiar Turkey instead) to escape religious persecution.

pg. 57 - Relics of St. Peter, St. Fevroniya, etc.
In the novel, the above list is inscribed on a bronze mount for a cross. The mentioned saints are important in Orthodox tradition; Sorokin's engraved cross would have served as a charm, to protect him against religious persecution.

pg. 58 - Faust and the Devil
Sorokin alludes to Johann Faust's as an example of the thoughtlessness of religious dogma and rules: i.e., one cannot "pray with conviction" if they had read Faust, nor can one believe in many religions - which, according to Sorokin, contradict each other.