God instituted marriage when He made a wife for Adam (Genesis 2:18). He instructed that a man should leave his father and mother and be joined to his wife, becoming one flesh with her (verse 24). God's will is for marriage to last for life—with each partner loving, honoring, caring for, and cleaving to the other just as Christ loves and cares for His church (Ephesians 5:25). The Bible teaches the sacredness of marital vows (Matthew 19:6; Mark 10:9; Romans 7:2-3; Hebrews 13:4).
However, we live in an imperfect world beset by human weakness, "hardness of heart," unfaithfulness, wickedness, irresponsibility, and all such things. People sin. Divorce occurs, even though God hates it, for it is a treacherous abandonment of the marriage covenant (Malachi 2:14-16).
What does one do if he or she has already been divorced? When a person repents and is converted, all his past sins are forgiven (Acts 2:38; Psalm 103:1-3, 10-12). Any past divorce would be included, and the person would be free to marry again but only to another within the church (II Corinthians 6:14; see Deuteronomy 7:1-4; 22:10).
What of those already converted? Paul wrote that those who have been divorced ("loosed") from an unbelieving mate do not sin if they marry (I Corinthians 7:27-28). Again, a converted person should marry within the church.
Paul was also inspired to write that a converted person must not leave or divorce a mate who is pleased to continue the marriage (verses 10-13). To divorce a faithful mate and marry another is adultery (Matthew 19:9). Divorce and remarriage is not sanctioned once God has entered the marriage and bound the couple for life (Matthew 5:32).
Although the unconverted world cannot receive God's teaching, all who are Christ's ought to obey Him implicitly, not only in refraining from divorce, but also in using all their resources to build a truly loving relationship (Ephesians 5:22-31; I Peter 3:1-7). Our earthly marriages ought to picture the great love relationship between Christ and the church (Ephesians 5:32; see Revelation 19:7-9).