Augustine of Hippo, On Nature and Grace Chapter 41: Whether Holy Men Have Died Without Sin

But there is clearly much acuteness in the question put by our author, “How must we suppose that those holy men quitted this life,—with sin, or without sin?” For if we answer, “With sin,” condemnation will be supposed to have been their destiny, which it is shocking to imagine; but if it be said that they departed this life “without sin,” then it would be a proof that man had been without sin in his present life, at all events, when death was approaching. But, with all his acuteness, he overlooks the circumstance that even righteous persons not without good reason offer up this prayer: “Forgive us our debts, as we forgive our debtors;” and that the Lord Christ, after explaining the prayer in His teaching, most truly added: “For if ye forgive men their trespasses, your Father will also forgive you your trespasses.” Here, indeed, we have the daily incense, so to speak, of the Spirit, which is offered to God on the altar of the heart, which we are bidden “to lift up,”—implying that, even if we cannot live here without sin, we may yet die without sin, when in merciful forgiveness the sin is blotted out which is committed in ignorance or infirmity.