Cyprian of Carthage, On the Unity of the Church 19

Those who despise God's tradition, chase after alien doctrines, and introduce human teachings as their authority are precisely the ones who imitate and follow such men. The Lord reproaches and rebukes them in His Gospel, saying, "You reject the command of God, so that you may establish your own tradition" (Mark 7:9). This crime is worse than the sin the lapsed appear to have committed; those, though established in penance for their crime, pray to God with full satisfaction. Here the Church is sought and entreated; there the Church is resisted. Here necessity may have been the cause; there the will is held fast in wickedness. The one who lapsed harmed only himself; the one who attempts heresy or schism deceives many by drawing them along with him. Here the loss is of a single soul; there the danger threatens many. The lapsed man certainly knows he has sinned, and he laments and mourns; the other swells with pride in his own breast, takes pleasure in his own offenses, separates children from their mother, lures sheep away from the shepherd, and disrupts God's sacraments. When the lapsed man sins once, that one sins daily. Finally, the lapsed man, if he later attains martyrdom, can receive the promises of the kingdom; but the other, if killed outside the Church, cannot attain the Church's rewards.