"Have mercy on me, O God, according to thy steadfast love;
according to thy abundant mercy blot out my transgressions.
Wash me thoroughly from my iniquity,
and cleanse me from my sin!
For I know my transgressions,
and my sin is ever before me.
Against thee, thee only, have I sinned, and done that which is evil in thy sight,
so that thou art justified in thy sentence and blameless in thy judgement.
Behold, I was brought forth in iniquity,
and in sin did my mother conceive me."
Psalm 51: 1-5
The Forgiveness of Sins
Even now, however, the angels are in concord with us when our sins are forgiven. So in our confession of faith the forgiveness of sins comes next in order after mention of the holy Church. It is because of this that the Church on earth stands, because of this that what was lost is found and does not perish. With the exception of the gift of baptism, which has been given to us against original sin, so that what was contracted through birth might be taken away through rebirth - and it also takes away actual sins which it finds to have been committed whether in the heart or the mouth or in deed - with the exception of this great forgiveness, the beginning of man's regeneration in which all guilt whether inborn or acquired is removed, the rest of our life once we have come to the age when we can use our reason, however rich it may be in fruits of justice, is not lived without forgiveness of sins, since God's children, for as long as they live this mortal life, are in conflict with death. The Augustine Catechism: The Enchiridion on Faith, Hope and Love; St. Augustine of Hippo, section 64.