Alright, let's stop taking the mickey and try to take it seriously:
The first problem is that sin is purely a religious concept and therefore doesn't exist for an atheist like me. To my mind things are wrong (roughly speaking) if they
(a) breach the laws of the land
(b) breach my own code of morals and ethics, which I don't suppose is much different from that of any other half-decent person.
What is and is not a sin depends on what religion you subscribe to.
To a Roman Catholic using a contraceptive is sinful, as is giving blood to a dying child to a Jehovah's Witness. To a Jew it is a sin to do any work at all on the Sabbath, even switching on an electric light. And so on.
So you can no more be 'wrong' about sin that you can be wrong about the rules of a club without specifying which club.
I can't trace the author, but if I were him/her I'd also keep a low profile!