4 Let every man examine his own conscience and let him deplore the violence he has done to it at every period of his life; and then when he has brought himself to deliver a true judgment on his own former misdeeds, let him give ear to the chiding of Jesus: “Thou hypocrite, first cast out the beam out of your own eye; and then shall you see clearly to cast out the mote out of your brother's eye.” Truly like the scribes and pharisees we strain out the gnat and swallow the camel, we pay tithe of mint and anise, and we omit the just judgment which God requires. What parallel can be drawn between a wife and a prostitute?
Is it fair to make a marriage now dissolved by death a ground of accusation, while dissolute living wins for itself a garland of praise? He, had his former wife lived, would not have married another; but as for you, how can you defend the bestial unions you indiscriminately make? Perhaps indeed you will say that you feared to contract marriage lest by so doing you might disqualify yourself for ordination. He took a wife that he might have children by her; you by taking a harlot have lost the hope of children.
He withdrew into the privacy of his own chamber when he sought to obey nature and to win God's blessing: “Be fruitful and multiply and replenish the earth.” You on the contrary outraged public decency in the hot eagerness of your lust. He covered a lawful indulgence beneath a veil of modesty; you pursued an unlawful one shamelessly before the eyes of all. For him it is written “Marriage is honourable and the bed undefiled,” while to you the words are read, “but whoremongers and adulterers God wilt judge,” and “if any man destroys the temple of God, him shall God destroy.” All iniquities, we are told, are forgiven us at our baptism, and when once we have received God's mercy we need not afterwards dread from Him the severity of a judge.
The apostle says:— “And such were some of you: but you are washed, but you are sanctified, but you are justified in the name of the Lord Jesus, and by the Spirit of our God.” All sins then are forgiven; it is an honest and faithful saying. But I ask you, how comes it that, while your uncleanness is washed away, my cleanness is made unclean? You reply, “No, it is not made unclean, it remains just what it was. Had it been uncleanness, it would have been washed away like mine.” I want to know what you mean by this shuffling.
Your remarks seem to have no more point in them than the round end of a pestle. Is a thing sin because it is not sin? Or is a thing unclean because it is not unclean? The Lord, you say, has not forgiven because He had nothing to forgive; yet because He has not forgiven, that which has not been forgiven still remains.
Source: Letters (New Advent)