Augustine explains the Creed to those soon to be baptized:
“The forgiveness of sins.” If this did not exist in the Church, there would be no hope. If there were no forgiveness of sins in the Church, there would be no hope of a future life and an eternal liberation. Thanks be to God who gave his Church this gift. You are about to come to the holy fountain; you will be washed by baptism; you will be renewed by the bath of regeneration; and you will be without sin when you come up out of that bath. All those past things that were pursuing you will be destroyed there. Your sins were like the Egyptians following, pursuing, the Israelites, but only up to the Red Sea. What does that mean: up to the Red Sea? Up to the fountain of Christ consecrated by the cross and blood of Christ. What is red makes red.... If you see the cross, notice the blood, too. If you see what is hanging there, notice what is flowing. The side of Christ was pierced by a lance and our price flowed out. Baptism is marked with the mark of Christ, that is, the water by which you were dyed and as it were passed through the Red Sea. Your sins are your enemies. They follow you, but only up to the sea. When you will enter that sea, you will escape and those sins will be destroyed, just as while the Israelites were escaping on to dry land, water covered the Egyptians. And what does Scripture say? “Not one of them remained” (Ps 105, 11). Whether you sinned many times or sinned few times, whether you sinned greatly or sinned slightly: not even the least of them remains.
But because our victory is in this world, where no one lives without sin, the forgiveness of sins does not consist only in the washing of sacred Baptism, but also in the daily Lord’s Prayer that you will receive in eight days. In that prayer you will find as it were your daily baptism, and you will give thanks to God who gave this gift to his Church, the one we confess in the Symbol when, after saying “holy Church,” we add: “the forgiveness of sins.” (Augustine, Sermon 215, 8, PL 38, 1065)