Nicene and Post-Nicene Fathers, Vol. III:
Doctrinal Treatises of St. Augustin: Section 16

16. In three ways then are sins remitted in the Church; by Baptism, by prayer, by the greater humility of penance; yet God doth not remit sins but to the baptized. The very sins which He remits first, He remits not but to the baptized. When? when they are baptized. The sins which are after remitted upon prayer, upon penance, to whom He remits, it is to the baptized that He remitteth. For how can they say, “Our Father,” who are not yet born sons? The Catechumens, so long as they be such, have upon them all their sins. If Catechumens, how much more Pagans? how much more heretics? But to heretics we do not change their baptism. Why? because they have baptism in the same way as a deserter has the soldier’s mark: 1806 just so these also have Baptism; they have it, but to be condemned thereby, not crowned. And yet if the deserter himself, being amended, begin to do duty as a soldier, does any man dare to change his mark?

Footnotes

“Characterem.”