SOURCE: John MacArthur
It was said, “Whoever sends his wife away, let him give her a certificate of divorce”; but I say to you that everyone who divorces his wife, except for the reason of unchastity, makes her commit adultery; and whoever marries a divorced woman commits adultery. – Matthew 5:31–32
Jesus no more approves of divorce than did Moses (cf. Matt. 19:6). Adultery, another reality God never condoned, is the only reason under the law that allows for dissolving of a marriage, with the guilty party to be put to death (Lev. 20:10). Because Jesus mentions this here and again in Matthew 19:9, God must have allowed divorce to replace execution as the penalty for adultery at some time during Israel’s history.
Divorce is never commanded; it is always a last resort, allowed when unrepentant immorality has exhausted the patience of the innocent spouse. This merciful concession to human sinfulness logically implies that God also permits remarriage. Divorce’s purpose is to show mercy to the guilty party, not to sentence the innocent party to a life of loneliness. If you are innocent and have strived to maintain your marriage, you are free to remarry if your spouse insists on continued adultery or divorce.
Jesus does not demand divorce in all cases of unchastity (immorality, primarily adultery in this context), but simply points out that divorce and remarriage on other grounds results in adultery.
Our Lord wants to set the record straight that God still hates divorce (Mal. 2:16) and that His ideal remains a monogamous, lifelong marriage. But as a gracious concession to those innocent spouses whose partners have defiled the marriage, He allows divorce for believers for the reason of immorality. (Paul later added the second reason of desertion, 1 Cor. 7:15.)