Let no Christian then stray from this faith, which alone is the Christian one; nor let any one, when he has been made to feel ashamed to say that we become righteous through our own selves, without the grace of God working this in us,—because he sees, when such an allegation is made, how unable pious believers are to endure it,—resort to any subterfuge on this point, by affirming that the reason why we cannot become righteous without the operation of God’s grace is this, that He gave the law, He instituted its teaching, He commanded its precepts of good. For there is no doubt that, without His assisting grace, the law is “the letter which killeth;” but when the life-giving spirit is present, the law causes that to be loved as written within, which it once caused to be feared as written without.
Reproduced in full. Translation: Nicene and Post-Nicene Fathers, series 1, vol. 5 (Schaff, 1887), public domain (Public domain).