I don't recall saying premarital sex should be banned or saying that homosexual couples shouldn't be allowed to marry. That is their business. Abortion is quite different. In that case, it is the murder of an innocent being who HAS no vote, and thus they must be fought for by those who do.
Now if you take your beliefs in politics out to their ends, we shouldn't illegalize murder, drugs, polygamy or anything like that. You wanna make those legal? If you do, I'd actually respect your position more. Right now you are jsut being contradictory.