Augustine of Hippo, On the Grace of Christ, and on Original Sin I.41: Restoration of Nature Understood by Pelagius as Forgiveness of Sins

In this same work he says in another passage: “Now, if even without God men show of what character they have been made by God, see what Christians have it in their power to do, whose nature has been through Christ restored to a better condition, and who are, moreover, assisted by the help of divine grace.” By this restoration of nature to a better state he would have us understand the remission of sins. This he has shown with sufficient clearness in another passage of this epistle, where he says: “Even those who have become in a certain sense obdurate through their long practice of sinning, can be restored through repentance.” But he may even here too make the assistance of divine grace consist in the revelation of teaching.