The Postniki (постники "fasters") were a millennial sect of 19th century Southern Russia, a branch of the Khlysty (flagellants) movement, founded by Abbakum (or Avvakum) Ivanov Kopylov (Аббакум / Аввакум Копылов, 1756–1838), a peasant of the Tambov Oblast. Kopylov declared himself the living Christ and gathered a considerable following in the 1820s. After Kopylov's death in 1838, the sect disintegrated in various schisms, giving rise to follow-up groups such as the Staroizrail (Old Israel) sect led by Kopylov's disciple Perfil Katasonov.
Soviet scholar A.I. Klibanov still encountered several postniki in Rasskazovo in 1959.
References
Postniki Wikipedia(Text) CC BY-SA