Letter 1
18 Moreover also the blessed Paul not only welcomes Onesimus the unprofitable runaway thief, because he was converted, but also asks his master to treat him who had repented, on equal terms of honour with his teacher, thus saying: “I beseech you for my son Onesimus, whom I have begotten in my bonds, who was aforetime unprofitable to you, but now is profitable to you and to me, whom I have sent back to you; thou therefore receive him, that is my very heart, whom I would fain have kept with me, that in your behalf he might minister unto me in the bonds of the Gospel; but without your mind I would do nothing that your goodness should not be as of necessity, but of free will.
For perhaps he was therefore parted from you for a season that you should have him back for ever; no longer as a servant, but above a servant, a brother beloved, specially unto me; but how much rather to you both in the flesh and in the Lord? If then you hold me as a partner, receive him as myself.” And the same apostle, in writing to the Corinthians, said, “Lest when I come I should mourn over many of those who have sinned beforehand and have not repented;” and again, “as I have said beforehand, so do I again declare beforehand, that if I come again I will not spare.” Do you see who they are whom he mourns, and whom he does not spare?
Not those who have sinned, but those who have not repented, and not simply those who have not repented, but those who have been called once and again to this work, and would not be persuaded. For the expression “I have said beforehand and do now say beforehand, as if I were present the second time, and being absent I write,” implies exactly that which we are afraid may take place now in our case. For although Paul is not present who then threatened the Corinthians, yet Christ is present, who was then speaking through his mouth; and if we continue obdurate, He will not spare us, but will smite us with a mighty blow, both in this world and the next.
“Let us then anticipate His countenance by our confession,” let us pour out our hearts before Him. For “you have sinned,” we read, “do not add thereto any more, and pray on behalf of your former deeds;” and again “a righteous man is his own accuser in the first instance.” Let us not then tarry for the accuser, but let us seize his place beforehand, and so let us make our judge more merciful by means of our candour. Now I know indeed that you confess your sins, and call yourself miserable above measure; but this is not the only thing I wish, but I long for you to be persuaded that it can justify you.
For as long as you make this confession unprofitable, even if you accuse yourself, you will not be able to desist from the sins which follow it. For no one will be able to do anything with zeal and the proper method, unless he has first of all persuaded himself that he does it to advantage. For even the sower, after he has scattered his seed, unless he expects the harvest, will never reap. For who would choose to fatigue himself in vain, if he was not to gain any good from his labor?
So then he also who sows words, and tears, and confession, unless he does this with a good hope, will not be able to desist from sinning, being still held down by the evil of despair; but just as that husbandman who despairs of any crop of fruit will not in future hinder any of those things which damage the seeds, so also he who sows his confession with tears, but does not expect any advantage for this, will not be able to overthrow those things which spoil repentance. And what does spoil repentance is being again entangled in the same evils.
“For there is one” we read, “who builds, and one who pulls down, what have they gained more than toil? He who is dipped in water because of contact with a dead body, and then touches it again, what has he gained by his washing?” Even so if a man fasts because of his sins, and goes his way again, and does the same things, who will hearken to his prayer? And again we read “if a man goes back from righteousness to sin the Lord will prepare him for the sword,” and, “as a dog when he has returned to his vomit, and become odious, so is a fool who by his wickedness has returned to his sin.”
Source: Two Letters to Theodore After His Fall (New Advent)