The Enchiridion by St. Augustine
Chapter 64.--Pardon of Sin Extends Over the Whole Mortal Life of the Saints, Which, Though Free from Crime, is Not Free from Sin.
But the angels even now are at peace with us when our sins are pardoned. Hence, in the order of the Creed, after the mention of the Holy Church is placed the remission of sins. For it is by this that the Church on earth stands: it is through this that what had been lost, and was found, is saved from being lost again. For, setting aside the grace of baptism, which is given as an antidote to original sin, so that what our birth imposes upon us, our new birth relieves us from (this grace, however, takes away all the actual sins also that have been committed in thought, word, and deed): setting aside, then, this great act of favor, whence commences man's restoration, and in which all our guilt, both original and actual, is washed away, the rest of our life from the time that we have the use of reason provides constant occasion for the remission of sins, however great may be our advance in righteousness. For the sons of God, as long as they live in this body of death, are in conflict with death. And although it is truly said of them, |As many as are led by the Spirit of God, they are the sons of God,| yet they are led by the Spirit of God, and as the sons of God advance towards God under this drawback, that they are led also by their own spirit, weighted as it is by the corruptible body; and that, as the sons of men, under the influence of human affections, they fall back to their old level, and so sin. There is a difference, however. For although every crime is a sin, every sin is not a crime. And so we say that the life of holy men, as long as they remain in this mortal body, may be found without crime; but, as the Apostle John says, |If we say that we have no sin, we deceive ourselves, and the truth is not in us.|