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.