Matthew 5:31 – 32

31 “Furthermore it has been said, ‘Whoever divorces his wife, let him give her a certificate of divorce.’

32 But I say to you that whoever divorces his wife for any reason except sexual immorality causes her to commit adultery; and whoever marries a woman who is divorced commits adultery.

Jesus is again showing differences in the new law and the old law. The old law allowed divorce for a multitude of reasons. Other scripture points out that God never intended for divorce to be allowed once a marriage was consummated. Marriage was considered to be a lifelong contract. Only death could break the marriage. But Christ said because of the hardness of the children of Israel's hearts Moses gave them the divorce option.(Matthew 19:8)

Christ says under the new law it will be different. The only valid reason for a man and woman to divorce was if sexual immorality was present within their marriage.

Let us be cautious in condemning those who have divorced, because Christ has in the preceding verses defined sexual immorality as being a condition of the heart as well as a physical action. The conditions of the heart we are not granted the liberty of being the judges of those sins. God is the only one who has the ability to read the minds and hearts of men. (1 Corinthians 4:5)