MobBoss
Off-Topic Overlord
I think there are a couple of exceptions, warpus - suicide being the one I hear about the most. It's supposed to be the one "unforgivable sin".
There is only one unforgiveable sin mentioned in the bible. Its not suicide.
Yes, Satan can repent and be forgiven.
I dont think that is in the cards, as he is probably one who has indeed committed the 'unforgivable sin' against the holy spirit. Or, at the very least, shouldnt the odds of him doing that be kind a high? I would think so.