Over fifty percent of all marriages in the United States end in divorce. The sad thing is, divorce occurs at relatively the same rate within the Church. That ought not to be. God's Word is clear; God hates divorce (Malachi 2:16). Jesus said, "Whosoever putteth away his wife and marrieth another, committeth adultery; and whosoever marrieth her that is put away from her husband committeth adultery" (Luke 16:18). Notice He does not allow for exceptions. However, in Matthew 5:31-32, Jesus seems to be saying that fornication is an exception, but fornication, in that sense, has to do with sexual immorality prior to marriage; otherwise, it would be adultery. The penalty for adultery was death, not divorce.
It is clear from Matthew 19:6 that Jesus did not agree with divorce, for once a couple is married, God viewed them as "one flesh." The Pharisees challenged Him by pointing out Moses taught that a man could simply give his wife a bill of divorcement, thus permitting divorce (Deuteronomy 24:1-2). Obviously this had to occur before the marriage was consummated, because she was permitted to go marry another. When the Pharisees asked the question, Jesus responded by saying Moses was permitted to allow divorce because God knew that men were stubborn. "He saith unto them, Moses because of the hardness of your hearts suffered (allowed) you to put away your wives; but from the beginning, it was not so."
God uses His relationship with Israel as a picture of how He views marriage. In the Book of Hosea, we find a metaphor for the marriage relationship. In it, God is represented by Hosea, who is told to marry a prostitute, who represents Israel (Hosea 1:2). Each time the wife (Israel) is unfaithful, Hosea (God) does whatever it takes to get her back. Here is a clear picture of how God views marriage. He is clearly "...longsuffering...not willing that any should perish, but that all should come to repentance" (2 Peter 3:9).
Everything I have written so far has to do with the Dispensation of the Law. While I am certain that God is consistent throughout all seven dispensations, there does seem to be a possible exception in the Dispensation of the Church. Paul makes it very clear that Christians are not to marry unbelievers (2 Corinthians 6:14). If a man or woman becomes a believer after they are married, Paul states they are not to leave their partner (1 Corinthians 7:10-24). But, if a Christian is married to an unbeliever, and the unbeliever chooses to leave, the believer is not to cause a problem, but do everything possible to maintain peace. Paul tells the Christian that they are no longer under bondage in such cases. This appears to allow for the Christian to remarry, but the context repeatedly suggests Christians remain single (verses 1, 7-8, 20, 24, 26, 32-34, 37-40). God does not hold us accountable for past actions done in ignorance, but once we know His will on a matter, to disobey is simply rebellion. Divorce is not the unpardonable sin.