An exert from "Blood: a Novel" by Patricia Traxler (God I hate rewriting shit)...

"I read once that sin is whatever obscures the soul...

...Maybe there is no such thing as sin.

But suppose there is an afterlife, a system of eternal rewards and punishments. Am I going to hell then? Are you?

The nuns said that if we thought it was a mortal sin to throw a pebble into a pond and we did it anyway, then we have in fact committed a mortal sin even though the act itself was not inherently sinful. All the light would go from our souls then, they told us, just as if we'd committed one of the most serious sins, like murder or adultery; and then if, say, we were hit by a bread truck or a bus on the way to school and died in that state, we would burn in hell with all the hardened felons of the world from all the years of humanity's stay on the earth. Forever.

Shouldn't it also work in the reverse then? So that if I don't believe a designated sin is actually a sin, then it's not?

Maybe, but that's if there is a God. If there is no God, then I have to depend on myself for mercy and understanding. It might get dicier that way."