Nicene and Post-Nicene Fathers, Vol. V:
A Treatise on the Merits and Forgiveness...: Chapter 3

Chapter 3 [III.]—In What Way God Commands Nothing Impossible. Works of Mercy, Means of Wiping Out Sins.

Now these people imagine that they are acute (as if none among us knew it) when they say, that “if we have not the will, we commit no sin; nor would God command man to do what was impossible for human volition.” But they do not see, that in order to overcome certain things, which are the objects either of an evil desire or an ill-conceived fear, men need the p. 45 strenuous efforts, and sometimes even all the energies, of the will; and that we should only imperfectly employ these in every instance, He foresaw who willed so true an utterance to be spoken by the prophet: “In Thy sight shall no man living be justified.” 447 The Lord, therefore, foreseeing that such would be our character, was pleased to provide and endow with efficacious virtue certain healthful remedies against the guilt and bonds even of sins committed after baptism,—for instance, the works of mercy,—as when he says: “Forgive, and ye shall be forgiven; give, and it shall be given unto you.” 448 For who could quit this life with any hope of obtaining eternal salvation, with that sentence impending: “Whosoever shall keep the whole law, and yet offend in one point, he is guilty of all,” 449 if there did not soon after follow: “So speak ye, and so do, as they that shall be judged by the law of liberty: for he shall have judgment without mercy that hath showed no mercy; and mercy rejoiceth against judgment?” 450

Footnotes

Ps. cxliii. 2.

Luke 6:37, 38.

Jas. ii. 10.

Jas. ii. 12.