1. If you love God, you will obey His instructions. Jesus said, "If you love Me, you will keep My commandments." (John 14:15) If your highest commitment is to Jesus Christ, then you won't compromise your convictions in this area.
2. Sex seals the covenant of marriage. After you have committed yourself to your spouse in the wedding, sex is that which seals the covenant. If you truly love your future spouse, you will wait until after you have committed yourselves to each other in the marriage ceremony. Many engaged couples have made the mistake of having sex before marriage because they were "going to" get married. Then, when they break off their engagement, they deeply regret having been involved sexually. It is the marriage ceremony, not the engagement, which commits you to one another.
3. God designed sex to be enjoyed only within the covenant of marriage. God will not allow sex to fulfill you outside of His purposes. However, God will put His blessing upon sex within marriage.
4. Sex makes you "one flesh" with another person. "Or do you not know that the one who joins himself to a prostitute is one body with her? For He says, 'The two shall become one flesh'." (1 Cor. 6:16). When you have sex with someone, you become one flesh with him or her-bound psychologically to some degree.
5. The person who has sex with numerous people becomes a fragmented person. Like a bee that goes from flower to flower, the person that has sex with others leaves a little bit of himself with each person.
6. Keep yourself pure for your future husband or wife. I've never met one person who regretted keeping himself or herself pure until marriage, but I have talked to multitudes of people who have regretted losing their virginity before marriage. You will not regret keeping yourself pure for God and your future spouse. It doesn't matter how many of your friends are doing it, don't give in to their pressure. Only YOU will live with yourself for the rest of your life. Your "friends" will quickly be gone and could care less about what is best for you. Don't sacrifice your future on the altar of the present, which will soon be past.