Melessa, most non-believers I know would NOT have experienced "comfort" in that belief system even at your DS' age. Only confusion because it didn't seem to be true, and everyone else seemed to believe it and find it comforting and expect us to feel the same way, too.
So it's possible that he's built for belief, if he finds comfort in it and is willing to accept as true those things that he is told.
It sounds to me as though he may be interested in "God as Mystery/Unknowable" as he matures, though. The "why" questions definitely lead that direction.
