Novatiajvs, a schismatical sect which originated in the 3d centurv, so called from their founder Novatian (Novatianus). He was a priest at Rome, who by his learning and eloquence won a high reputation. It has been inferred from uncertain data that he professed the stoic philosophy before becoming a Christian; and he was distinguished after his baptism by his rigid ascetic life. He held that persons who had committed the more grievous sins, and especially those who had denied their faith during the Decian persecution, ought not to be received again into the church. One of the foremost defenders of the contrary opinion was the priest Cornelius, who in 250 succeeded Fabian in the see of Rome. Novatian, unable to prevent his election, withdrew from communion with him, was excommunicated by a council held at Rome in 251, and was almost immediately afterward set up as a rival bishop by his own party. He tried in vain to obtain fellowship with the great churches of Antioch, Alexandria, and Carthage, but found his principal coadjutor in Novatus, a Carthaginian priest, known by his opposition to St. Cyprian. Though differing widely on the administration of public penance, they agreed in their notions about the constitution of the church.

According to Novatian, the chief character of the true church is purity and holiness. Every church society that tolerates in its bosom or readmits to its communion persons who by gross sins have broken their baptismal vows, ceases by that very act to be a true Christian church. Hence the Novatians, considering themselves to be the only pure church, called themselves ol Kadapoi, " the pure." They also held that members are made impure by outward connection with the impure in the same communion, and that the ministerial powers transmitted in the hierarchy are lost by the same cause. The sect survived its founder about three centuries.