Eternal sin
In Christian hamartiology, eternal sins, unforgivable sins, or unpardonable sins are sins which will not be forgiven by God. One eternal or unforgivable sin (blasphemy against the Holy Spirit) is specified in several passages of the Synoptic Gospels, including , , and .
Sacrament of Penance
Practically all writings of that period, for instance "The Shepherd of Hermas", "Didache" or "Letters of St. Ignace of Antioch", show that grave sins were not rare among Christians. Cyrille Vogel collected a list of twelve major sins named in the New Testament and the Apostolic Fathers' writings. They are all various transgressions of the Ten Commandments: