The grounds for divorce given in the Bible sound constricting to modern ears. The teachings on divorce address the issues of the day, which were very different than modern times. Add to that some seemingly contradictory passages and confusing turns of phrase, and things get even muddier.
What grounds for divorce does the Bible provide?
When God first created the marriage relationship, divorce was not a part of the plan. Fallen man, as he often does, defiled God's intent for His creation. When the Pharisees asked Jesus if a man could divorce his wife at will, Jesus responded:
He answered, "Have you not read that he who created them from the beginning made them male and female, and said, 'Therefore a man shall leave his father and his mother and hold fast to his wife, and the two shall become one flesh'? So they are no longer two but one flesh. What therefore God has joined together, let not man separate" (Matthew 19:4-6)
When asked about grounds for divorce in the time of Moses, Jesus said, "Moses permitted you to divorce your wives because your hearts were hard. But it was not this way from the beginning. I tell you that anyone who divorces his wife, except for sexual immorality, and marries another woman commits adultery" (Matthew 19:8-9). In the Old Testament, God allowed divorce if a man's heart became so hardened against his wife that she was actually better off without him—a rare and extreme circumstance in a time where women had very few legal rights. This was the purpose of the dowry—presumably the husband had set aside money at the beginning of their marriage to see to his bride's needs should he abandon her by death or divorce.
As Jesus mentioned, this was not God's intent for marriage. Marriage was to be a permanent illustration of God's love and devotion to Israel. If a man was cruel or abusive to his wife, he was not reflecting the kind, forgiving spirit of God. A man who divorced his wife under such circumstances was not to marry again; God was faithful to the "wife of His youth" despite Israel's spiritual adultery (Malachi 2:14), and a man who couldn't love his wife as God loved Israel was not worthy of getting a new wife. As Malachi 2:16 (NIV) says, "The man who hates and divorces his wife…does violence to the one he should protect."
Taken in the whole, a man was not to divorce his wife unless she was unfaithful, or he was abusive and the divorce was protection for the wife. If the divorce was not because of unfaithfulness on her part, he was not allowed to remarry (Matthew 19:9).
These were the grounds for divorce for Israel, but the church age is slightly different. A wife had few people to protect her from her husband in the Old Testament; a wife in the latter New Testament and beyond has the church. Matthew 18:15-17 describes the steps of reconciliation Christians should take in their relationships and dealings with others: confront privately, seek counseling, take it to the church.
First Corinthians 7:10-16 describes grounds for divorce for believers. First of all, believing spouses are assumed to be led by the Holy Spirit, not their own selfish desires. Believers are supposed to work with the Spirit in the process of sanctification, growing from glory to glory as they strive to be more like Christ. This, combined with Matthew 18:15-17, should resolve any issue that would otherwise lead to divorce. If both spouses are humble and patient and kind and loving, and live with a healthy, supportive church, they should have the tools to successfully wade through any issue.
First Corinthians 7:10-11 allows that this doesn't always happen. Those who are immature in the faith may not have the spiritual tools to weather difficult marriages. Paul is clear: marriage is an illustration of God's relationship with the church (Ephesians 5:32). That relationship is supposed to be faithful and permanent. Divorce and remarriage is not appropriate for personal difficulties. Although it is certainly not ideal, separation with the goal of reconciliation is allowed.
The Bible also describes grounds for divorce if one spouse is a believer but the other is not. Ideally, it is better for them to remain together. The godly influence of the Christian spouse will bring peace and blessing to the family that would be removed if the marriage were dissolved. The non-Christian will be subtly influenced by the loving behavior of the believing spouse. But if the unbelieving spouse leaves, the Christian is required to let him go. In modern times, this means that if the unbelieving spouse files for divorce, the Christian must sign the paperwork.
Not all believers live out their faith. Often, one spouse will be closer to the Lord than the other. First Corinthians 7:12-16 addresses this situation as well. The last statement in the steps of resolution Jesus gives in Matthew 18:15-17 says that if every avenue has tried and failed, the sinner is to be considered as "a Gentile and a tax collector"—that is, as an unbeliever. If it comes to this, the same rules apply: if steps of reconciliation have been followed but one believing spouse still files for divorce, the other must sign.
These passages describe the biblical grounds for divorce: adultery and abandonment. Adultery because it defiles God's use of marriage to represent His love for Israel and the church. Abandonment because we are called to live in peace. This can be very hard to swallow for those who feel they are trapped in a loveless marriage. But our relationship with God is to be above our relationship with others. Our personal and corporate commandment is "love God, love others." There is no better way to love others than to do what we can to draw them to God. Sometimes we need a break, and sometimes a partner can completely destroy any chance we have to reach them. But through any situation, God can lead us through a way in which we will not sin—which is faithfulness to Him (1 Corinthians 10:13).
What are biblical steps to restore a marriage?
Is abuse a biblical reason to divorce?
In marriage how do the two become one flesh?
What is the biblical view on divorce and remarriage?
If a person divorces and remarries, is it always going to be adulterous?
Truth about Marriage