You don't believe in sin?
What if I murder some one in cold blood, for no reason at all? Is that sin? And if it is a sin, who am I sinning against? The person? perhaps. But who said I can't murder some one in cold blood for no reason at all? the person? perhaps. But who gave that person the right to make the law for my life? What if my law says it is ok to murder some one in cold blood for no reason.
See where I'm going?
There are things that are wrong in this world. Whether you want to see it or not.
Even if the government had no laws against murder, murder is still a sin. Why? Cause there is a Rule Maker (God) who said that murder is wrong.
If your the god of your own universe and I'm the god of my own universe, and every one else is there own god, then whose to say that the murderers and theifs and rapers are bad, when they to are following their own rules that they've made? See God made rules for this world, and man does not want to follow those rules. Sooooooo man now tries to make his own rules and shut God out, but he will find that God's rules are what he needs.