Answer: Novatianism was a sect that split from mainstream Christianity in the 3rd century. The sect was more or less extinct by the 8th century. The Novatianists preferred to call themselves katharoi, literally meaning “clean.” Novatianism split from Roman Christianity over a dispute regarding apostasy and how to deal with church members who had committed grievous sins. While in agreement on all other doctrinal points, Novatianism differed on issues of apostasy and church authority.

During a period of heavy persecution in the 3rd century, Fabian, the Bishop of Rome, was martyred. The persecution left church leadership in a bit of a shambles, and there were disagreements over how to restore it. One of the key disagreements was how to handle those who had professed faith prior to the persecution but denied Christ under duress. Most bishops favored some form of reconciliation, with different views on what kind of penance would be required. Cyprian of Carthage led the movement to re-admit into the church these “lapsed” Christians who had fallen away during the persecution.

Novatian, however, strongly disagreed with Cyprian. According to Novatian, anyone who denied Christ, even under persecution, could not be forgiven by the church. Strictly speaking, he held they might possibly be forgiven by God, but such forgiveness could not be offered by the church itself. In essence, Novatian claimed that in certain instances the earthly church had no right to offer absolution.

When Cornelius was selected to replace the martyred Fabian, Novatian was incensed—the decision was a direct refutation of his hardline stance on lapsed Christians. In response, Novatian convened with a few other bishops and declared himself the Bishop of Rome. In effect, Novatian attempted to take over the Christian church in opposition to most of the existing leaders. For this action, he was excommunicated, and his teachings were declared heresy.

Novatianism taught that certain sins were “mortal,” at least so far as the earthly church was concerned. Mortal sins included apostasy, adultery, idolatry, and so forth. According to the Novatian view, anyone guilty of such sins was outside the church’s power to offer forgiveness. Such sinners might be pardoned by God, but they could not be admitted back into the congregation nor offered sacraments nor given absolution. Other than this view, the Novatian doctrinal stance was identical to the rest of mainstream Christianity at the time.

Over the next few centuries, adherents of Novatianism experienced varied measures of tolerance and harassment from the orthodox church. Though Emperor Constantine invited representatives of Novatianism to the Council of Nicea, the group’s influence rapidly faded. By the 5th century, Novatianism was all but absent in the Roman Church, and by the 8th century it was extinct among the Eastern Orthodox Church, as well.