This episode of Matthew chapter 5 speaks of the heart in regard to adultery in the heart and of marriage which is supposed to be sacred and binding, but not always the case.  

The marriage ordained by God: God's will for marriage is one mate, one marriage for life. To this Jesus gives an exception namely, "fornication." Fornication is marital unfaithfulness and includes adultery or any kind of sexual immorality. Hence, divorce is to be permitted when sexual immorality is involved. The following are important Biblical facts concerning divorce.

1. When Jesus criticizes divorce in Matt. 19:7-8, He is not criticizing a separation because of adultery, but a divorce permitted in the O.T. in those cases where a husband discovered premarital unchastity after the marriage ceremony had taken place (Deut. 24:1-4). God's desire in such cases was that the two remain together. However, He permitted divorce due to premarital unchastity because of the hardness of the people's hearts (vv. 7-8). 

2. In the case of immorality after marriage, the O.T. law prescribed the dissolving of the marriage by executing both the offending parties (Lev. 20:10; Deut. 22:22). This, of course, would leave the innocent person free to remarry (Rom. 7:2; 1 Cor. 7:39). 

3. Under the new covenant the privileges of the believer are no less. Although divorce is a tragedy, marital unfaithfulness is such a cruel sin against one's mate that Christ states that the innocent party has a proper right to end the marriage by a divorce based on adultery. He or she is free to remarry another believer (1 Cor. 7:27-28).

4. Paul's treatment of marriage and desertion in 1 Cor. 7:12-16 indicates that marriage also may be dissolved by the desertion of an unbelieving spouse. He further indicates that remarriage by the believer in such cases is not a sin.

FL commentary

Blessings

Elder Barbara