I don't think premarital sex and some other stuff is a sin. I mean the law against premarital sex was never given to man by God or Jesus or any prophet. It was made up by priests. One big part of Joeism is you only believe what God, or any prophet says. Not anything said by a man, because men make mistakes. But laws of governments need to be followed because it is right and there are consequences.
Joeism has a few flaws. The Bible, which states what God/Jesus "said" was compiled by a bunch of men. A bunch of figures in the Roman Catholic Church gathered around a table and decided what was going to go into the Bible. And... the Bible was not written by God or any other holy force. It was written by man. And, you are right -- man does have flaws.
And, right to follow the law, perhaps, if you feel the law is just. Right also to break the law, if you have moral convictions (i.e. you aren't going to join the SS in the deportation of Jews or some historical thing like that... or with what is going down in the Sudan). Just saying. The law isn't
always right. However, most of the laws in our society are sound, in the sense that there is some logic behind them, at least. And by logic I mean the statutory rape laws, etc. Tragic flaws include when younger participants pose as older and get the 'rapists' in trouble with the law. Not fair at all.
The law is just as correct and fair as the people who draft it.
And, by the way, you said you were young and stupid. You aren't young and stupid, as to even have an opinion on one of these subjects shows some intelligence!