I would like to say that the "original sin" is the desire of most humans to be free, to think for themselves, and to make moral decisions for themselves. In my view, there can be no true morality without freedom. To the religious mind, though, a mind who sees human existence as that of a servant of the god or gods, this is unacceptible. To religion, freedom is a great danger and a step toward breaking god's rules. So throughout history we have this dialectic: mankind is free but everywhere lies in chains, enchaining himself and enchaining others.
Break the chain, practice the path of understanding, seek truth.