What trouble the sin of adultery has brought upon the human race. Think of how different our world would be if we would just keep this single commandment. Think of how different the lives of so many people would have been if they had not committed this sin. How many divorces would have been avoided? How many families would still be together? How many fathers would still be at home to raise their children?
Adultery is being unfaithful to your spouse. If you are single, having sex before marriage is called fornication. What does God say about adultery and fornication? Hebrews 13:4 "God will surely judge people who are immoral and those who commit adultery."
When a man and woman come together sexually, they enter a state of oneness. In fact, 1 Corinthians 6:15–16 says, "Don't you realize that your bodies are actually parts of Christ? Should a man take his body, which is part of Christ, and join it to a prostitute? Never! And don't you realize that if a man joins himself to a prostitute, he becomes one body with her? For the Scriptures say, 'The two are united into one.' "
Understand, God has given us a sexual drive just as surely as He created the family and brought a man and a woman together. Sometimes we forget that God thought up sex. He invented it. But sometimes the Christian view of sex is mischaracterized. Some assert that Christians believe sex is only for procreation. We do believe it is for that, but God has given it to us for pleasure as well. He has given it to us for fulfillment. It is something that He can really bless. But there is only one place God will bless it, and that is in a marriage relationship.