I think it's a sign of being someone who's very concerned with morality. Your answer was very articulate for a 9 year old, and your feelings about your friend's answer impressed me. I'd say they reveal someone with a strong desire to be good, moral.

I didn't find it funny so much as heartbreaking. I generally think adults ought to be very careful about proposing moral questions this way. I would have wanted to protect a 9 year old from forming that sort of conclusion about himself - at the least, help him have a perspective about it.

I agree with the person who said that it wasn't really appropriate for a teacher to put children on the spot with answering that question. It might have been an interesting question to have you think over and possibly to write about but not to share with everyone - and even then, only after giving some guidance - such as what Woty said about no one else being close enough to God to really be able to fully conceive of doing such a thing.