The 19th century Middle Volga region represented a polyethnic and multicultural entity. In the second half of the century the religious sphere of life of indigenous peoples had become complexly challenged. Orthodoxy was either imposed on them by the Russian empire or came to blend with their culture through voluntary baptism, mixed marriages and monopoly of the Orthodox faith in the Russian administrative system. The imperial assimilative attempts, however, met the resistance of the indigenous population which manifested itself in the apostasies of 1860s, when Islamic proselytism, being the result of the rising national movement among the Tatar people, resulted in the conversion of Kriashen (baptized Tatars) and pagans into Muslim faith. The process caused immediate reaction of the authorities, introducing the whole system of education of non-Russian peoples named after its founder N.I. Il''minskii. The policy of training and recruitment of teachers and clergy from non-Russian milieu and the promotion of literature in indigenous languages contributed to the solution of urgent imperial problems.