19 These, doubtless, they imitate and follow, who, despising God's tradition, seek after strange doctrines, and bring in teachings of human appointment, whom the Lord rebukes and reproves in His Gospel, saying, “You reject the commandment of God, that you may keep your own tradition.” This is a worse crime than that which the lapsed seem to have fallen into, who nevertheless, standing as penitents for their crime, beseech God with full satisfactions. In this case, the Church is sought after and entreated; in that case, the Church is resisted: here it is possible that there has been necessity; there the will is engaged in the wickedness: on the one hand, he who has lapsed has only injured himself; on the other, he who has endeavoured to cause a heresy or a schism has deceived many by drawing them with him.
In the former, it is the loss of one soul; in the latter, the risk of many. Certainly the one both understands that he has sinned, and laments and bewails it; the other, puffed up in his heart, and pleasing himself in his very crimes, separates sons from their Mother, entices sheep from their shepherd, disturbs the sacraments of God; and while the lapsed has sinned but once, he sins daily. Finally, the lapsed, who has subsequently attained to martyrdom, may receive the promises of the kingdom; while the other, if he have been slain without the Church, cannot attain to the rewards of the Church.
Source: The Treatises of Cyprian (New Advent)