Divorce has never been pretty. And it has never been God’s design. Unfortunately, many of us know this from a first-hand perspective. Divorce is never pretty because it erodes at the prettiness of marriage. However, divorce is not always a sin; Jesus makes that clear in Matthew 5 and Matthew 19. Yet, all that leads to divorce is sin.
Jay Adams made this phrase popular in the 70’s in his work entitled Marriage, Divorce, and Remarriage. But it is really a simply expression of a biblical truth. It starts in Matthew 5:31-32 where Jesus reorients the idea of divorce. In this passage, Jesus is reiterating the importance of the Law and explaining the intent of the Law again in regards to divorce. In doing so He reels in what was becoming commonplace in this time for divorce, which was that you could simply issue a bill of divorce over small matters. The people of this time took the words of Deuteronomy and applied it to the smallest degree. Women were divorced over seemingly insignificant things. Historians say that, this law “permitted a man to divorce his wife if she spoiled his dinner (Mishnah Giṭ. 9.10; … [other accounts say divorce was allowed] “Even if he found another fairer than she.” This now makes sense when you hear the question the Pharisees asked Jesus, “Is it lawful for a man to put away his wife for every cause?” (Matt. 19:3). In this time, divorce was becoming very common perhaps more common than in our modern day.
Yet in that commonality, Jesus provides one clear reason for divorce: unrepentant sexual immorality. The word that Jesus uses in both Matthew 5 and Matthew 19 is a word that simply indicates sexual acts that are morally objectionable. It was also connected with unlawful sexual intercourse. Most would not put this into a specific type of sin, like incest, but believe this word represents sexual sin as a whole. This is what Joseph was planning on doing with Mary when he found out she was pregnant; he was going to divorce her quietly. The grounds that Jesus provides is that when a spouse has engaged in sexual sin and is unrepentant of that sexual sin, you have the right to divorce them. Now you must distinguish in your mind the fact that God did not institute divorce, He only regulated it. Jesus said because of the hardness of your heart Moses allowed you to issue a certificate of divorce. Most likely this is so that people would not continue to take advantage of each other and worsen an already bad situation.
Christ does not command the people of this time to divorce if their spouse has committed sexual sin. Rather, He has said that they may divorce them if they are unrepentantly committing sexual sin. And I say unrepentantly committing sexual sin because if they commit sexual sin and repent, Christ says we have an obligation to forgive them (Matt. 6:14). Forgiveness means that you will not divorce, for forgiveness means you will not let that infraction come between you. Therefore, if your spouse commits a sexual sin and repents, you have an obligation to forgive them.
Jesus has again reoriented what the Jews of this time were expecting. And in that reorientation instead of divorcing your wife for whatever, as long as you give her a bill of divorce, He shows that divorce is only permissible under the circumstance of unrepentant sexual immorality. And Paul later tells us that abandonment is also a legitimate reason for divorce. And if you have divorced your spouse for an unbiblical reason, you are causing them to commit adultery because your divorce is not legitimate even though it is legal. There is no easy way to say this; divorce is not always a sin but all that leads to divorce is. And it again reminds us of what the disciples said in Matthew 19: “If this is true, then it is better not to marry.”
 Logos 6, s.v. “porneia.”
 BDAG, s.v. “porneia.”
 Jay Adams, Marriage, Divorce, and Remarriage (Grand Rapids: Zondervan, 1980), 51.
 Leon Morris, The Gospel According to Matthew, The Pillar New Testament Commentary (Grand Rapids, MI; Leicester, England: W.B. Eerdmans; Inter-Varsity Press, 1992), 120.