Your definition of sin is quite different from what many (including me probably) will have to say, but I think I am begining to like it. If I am to speak as a Christian, morality and sin might not completely be same since there are some sin that are not necessarily amoral [if we are to consider it from the legal point of view]. That aside, I am yet to agree with the fact that a world characterised by struggles for survival will be void of sin; even sin as to morality.
It was nice coming across your post @whywhy, this is probably the most philosophical writing I have read in a long time.