The answer to this question depends somewhat on what is meant by “living together.” If it means having sexual relations, it is definitely wrong. Premarital sex is repeatedly condemned in Scripture, along with all other forms of sexual immorality (Acts 15:20; Romans 1:29; 1 Corinthians 5:1; 6:13, 18; 7:2; 10:8; 2 Corinthians 12:21; Galatians 5:19; Ephesians 5:3; Colossians 3:5; 1 Thessalonians 4:3; Jude 7). The Bible promotes complete abstinence outside of (and before) marriage. Sex before marriage is just as wrong as adultery and other forms of sexual immorality, because they all involve having sex with someone you are not married to.
If “living together” means living in the same house, that is perhaps a different issue. Technically, there is nothing wrong with a man and a woman living in the same house—if there is nothing immoral taking place. However, the problem arises in that there is still the appearance of immorality (1 Thessalonians 5:22; Ephesians 5:3), and it could be a tremendous temptation for immorality. The Bible tells us to flee immorality, not expose ourselves to constant temptations to immorality (1 Corinthians 6:18). Then there is the problem of appearances. A couple who is living together is assumed to be sleeping together—that is just the nature of things. Even though living in the same house is not sinful in and of itself, the appearance of sin is there. The Bible tells us to avoid the appearance of evil (1 Thessalonians 5:22; Ephesians 5:3), to flee from immorality, and not to cause anyone to stumble or be offended. As a result, it is not honoring to God for a man and a woman to live together outside of marriage.
Although the words “courtship” and “dating” are not found in the Bible, we are given some principles that Christians are to go by during the time before marriage. The first is that we must separate from the world’s view on dating because God’s way contradicts the world’s (2 Peter 2:20). While the world’s view may be to date around as much as we want, the important thing is to discover the character of a person before making any commitment to him or her. We should find out if the person has been born again in the Spirit of Christ (John 3:3-8) and if he or she shares the same desire toward Christ-likeness (Philippians 2:5). The ultimate goal of dating or courting is finding a life partner. The Bible tells us that, as Christians, we should not marry an unbeliever (2 Corinthians 6:14-15) because this would weaken our relationship with Christ and compromise our morals and standards.
When one is in a committed relationship, whether dating or courting, it is important to remember to love the Lord above all else (Matthew 10:37). To say or believe that another person is “everything” or the most important thing in one’s life is idolatry, which is sin (Galatians 5:20; Colossians 3:5). Also, we are not to defile our bodies by having premarital sex (1 Corinthians 6:9, 13; 2 Timothy 2:22). Sexual immorality is a sin not only against God but against our own bodies (1 Corinthians 6:18). It is important to love and honor others as we love ourselves (Romans 12:9-10), and this is certainly true for a courtship or dating relationship. Whether dating or courting, following these biblical principles is the best way to have a secure foundation for a marriage. It is one of the most important decisions we will ever make, because when two people marry, they cleave to one another and become one flesh in a relationship which God intended to be permanent and unbreakable (Genesis 2:24; Matthew 19:5).
Since 1 Corinthians 7:2 clearly includes sex before marriage in the definition of sexual immorality, all of the Bible verses that condemn sexual immorality as being sinful also condemn sex before marriage as sinful. Sex before marriage is included in the biblical definition of sexual immorality. There are numerous Scriptures that declare sex before marriage to be a sin (Acts 15:20; 1 Corinthians 5:1; 6:13, 18; 10:8; 2 Corinthians 12:21; Galatians 5:19; Ephesians 5:3; Colossians 3:5; 1 Thessalonians 4:3; Jude 7). The Bible promotes complete abstinence before marriage. Sex between a husband and his wife is the only form of sexual relations of which God approves (Hebrews 13:4).
Far too often we focus on the “recreation” aspect of sex without recognizing that there is another aspect—procreation. Sex within marriage is pleasurable, and God designed it that way. God wants men and women to enjoy sexual activity within the confines of marriage. Song of Solomon and several other Bible passages (such as Proverbs 5:19) clearly describe the pleasure of sex. However, the couple must understand that God’s intent for sex includes producing children. Thus, for a couple to engage in sex before marriage is doubly wrong—they are enjoying pleasures not intended for them, and they are taking a chance of creating a human life outside of the family structure God intended for every child.
While practicality does not determine right from wrong, if the Bible’s message on sex before marriage were obeyed, there would be far fewer sexually transmitted diseases, far fewer abortions, far fewer unwed mothers and unwanted pregnancies, and far fewer children growing up without both parents in their lives. Abstinence is God’s only policy when it comes to sex before marriage. Abstinence saves lives, protects babies, gives sexual relations the proper value, and, most importantly, honors God.