Luke 16:18

But we must first speak, I think, of the law of marriage, that we may afterwards discuss the forbidding of divorce. Some think that all marriage is sanctioned by God, because it is written, Whom God hath joined, let not man put asunder. (Matt. 19:6.) How then does the Apostle say, If the unbelieving depart, let him depart? (Mark 10:9, 1 Cor. 7:15.) Herein he shows that the marriage of all is not from God. For neither by God's approval are Christians joined with Gentiles. Do not then put away thy wife, lest thou deny God to be the Author of thy union. For if others, much more oughtest thou to bear with and correct the behaviour of thy wife. And if she is sent away pregnant with children, it is a hard thing to shut out the parent and keep the pledge; so as to add to the parents' disgrace the loss also of filial affection. Harder still if because of the mother thou drivest away the children also. Wouldest thou suffer in thy lifetime thy children to be under a step-father, or when the mother was alive to be under a step-mother? How dangerous to expose to error the tender age of a young wife. How wicked to desert in old age one, the flower of whose growth thou hast blighted. Suppose that being divorced she does not marry, this also ought to be displeasing to you, to whom though an adulterer, she keeps her troth. Suppose she marries, her necessity is thy crime, and that which thou supposest marriage, is adultery. But to understand it morally. Having just before set forth that the kingdom of God is preached, and said that one tittle could not fall from the Law, He added, Whosoever putteth away his wife, &c. Christ is the husband; whomsoever then God has brought to His son, let not persecution sever, nor lust entice, nor philosophy spoil, nor heretics taint, nor Jew seduce. Adulterers are all such as desire to corrupt truth, faith, and wisdom.

For that to the imperfect the Law spoke imperfectly is plain from what he says to the hard hearts of the Jews, "If a man hate his wife, let him put her away," (Deut. 24:1.) because since they were murderers and rejoiced in blood, they had no pity even upon those who were united to them, so that they slew their sons and daughters for devils. But now there is need of a more perfect doctrine. Wherefore I say, that if a man puts away his wife, having no excuse of fornication, he commits adultery, and he who marrieth another commits adultery.

But lest they should suppose that in His words, the Law and the Prophets were until John, He preached the destruction of the Law or the Prophets, He obviates such a notion, adding, And it is easier for heaven and earth to pass, than one tittle of the law should fail. For it is written, the fashion of this world passeth away. (1 Cor. 7:31.) But of the Law, not even the very extreme point of one letter, that is, not even the least things are destitute of spiritual sacraments. And yet the Law and the Prophets were until John, because that could always be prophesied as about to come, which by the preaching of John it was clear had come. But that which He spoke beforehand concerning the perpetual inviolability of the Law, He confirms by one testimony taken therefrom for the sake of example, saying, Whosoever putteth away his wife, and marrieth another, committeth adultery: and whosoever marrieth her that is put away from her husband, committeth adultery; that from this one instance they should learn that He came not to destroy but to fulfil the commands of the Law.