Premarital sex

This is a very touchy subject. For some, like me, it would mean that one had denied him/herself, in vain - sometimes for many years. I find nothing in the Bible specifically listing premarital sex a sin, not even in the big list of sins in Leviticus 18, where the Lord details unlawful sexual sins, which include (in graphic detail) incest, bestiality and apparently homosexuality. Some people have said that just because it isn't in the list, doesn't mean it is not a sin. I disagree with that position. Who is able to determine what is a sin or not? God. Man is incapable to determine that. Sin is whatever God says it is, not what you say it is. So, if there is no law against something, it's not a sin to do it.