What if a man cannot wait? What if a man really wants to have sex with a girl? What should the man do?
"Now concerning the things of which you wrote to me: It is good for a man not to touch a woman. Nevertheless, because of sexual immorality, let each man have his own wife, and let each woman have her own husband. ... But I say to the unmarried and to the widows: It is good for them if they remain even as I am; but if they cannot exercise self-control, let them marry. For it is better to marry than to burn with passion" (I Corinthians 7:1-2, 8-9).
Paul's advice is given knowing that Christians would soon be facing severe persecution. "I suppose therefore that this is good because of the present distress--that it is good for a man to remain as he is" (I Corinthians 7:26). It is one thing to face threats on my life because of my belief in Christ, but it is another thing if my wife and children are threaten because of my belief. Many people would not have the strength of faith to resist such persecution. Hence, Paul recommended that people avoid marriage during the times of persecution.
However, Paul also understood that sexual desire is very strong in many people. Many can talk about refraining from sex in theory, but that restraint will cause them to be easily tempted to have sex outside of marriage. The answer is straight forward: get married. Then you will have a proper outlet for your sexual desire.
I know that in some regions of the world this is much easier said than done. For example, I know that in the Philippines a man and woman cannot marry before they reach the age of 18. Between 18 and 28 they cannot marry unless they have the permission of their parents. The result has been that many couples go ahead and engage in fornication (sex outside of marriage) before they are 28, knowing that if the woman becomes pregnant -- well, Mom and Dad will feel that they have to give permission to marry. Though the law has good intentions, it creates an environment where sin is rampant.
I don't know your age, but generally the male sex drive peeks in a man's early twenties. If you have not reached the age when you can legally marry, then you will have to wait. I'm sure it has been several years since you discovered your sex drive. You managed to get this far without sex, surely you can wait a few more years. If you are in the age range where you could marry, but you need your parents' permission, then calmly sit down with them and explain that you are having difficulty waiting. Demonstrate that you are prepared to take on the responsibility of caring for a wife and supporting a family. Discuss with them what you plan to do when a baby arrives because births do have costs associated with them. In other words, show yourself to be a man and not a sex crazed adolescent. It is very likely that your parents will not only understand, but they will be proud to have you and your girlfriend joined in marriage.
Questions and Answers regarding Sexual Relations
Questions and Answers regarding Lust
Articles on Sexual Sins
"Waiting for the Proper Time" in Preparation for a Lifetime
"Why Sex Outside of Marriage is Wrong" in Preparation for a Lifetime