These passages from Augustine came up in our recent discussion of John Wesley’s ideas of perfectionism.
Augustine, On Nature and Grace
“If, therefore, we feel rightly on this matter, it is our duty at once to be thankful for what is already healed within us, and to pray for such further healing as shall enable us to enjoy full liberty, in that most absolute state of health which is incapable of addition, the perfect pleasure of God. For we do not deny that human nature can be without sin; nor ought we by any means to refuse to it the ability to become perfect, since we admit its capacity for progress—by God’s grace, however, through our Lord Jesus Christ. By His assistance we aver that it becomes holy and happy, by whom it was created in order to be so.”
“Now, whether there ever has been, or is, or ever can be, a man living so righteous a life in this world as to have no sin at all, may be an open question among true and pious Christians; but whoever doubts the possibility of this sinless state after this present life; is foolish. For my own part, indeed, I am unwilling to dispute the point even as respects this life.”