ARRGGGGHH.
ALL OF US have a reason to live by the Golden Rule.
It's just that we don't. If we did the Crucifixion would never have needed to occur.
And who says everyone wants to live in peace?
And I do hope tortoise's Iterated Prisoner Dilemma claim is correct. It would give mathematical backing to a the teachings of Jesus.
Weeeeeelllll... Be careful what you wish for! If it gives mathematical backing to the teachings of Jesus, then that would really hurt the claim that Jesus/God himself must be the source of the truth of those teachings.
It's kinda like the parable of the Talents. The moral of the story is, invest your money instead of stuffing it into a mattress. (Or metaphorically, don't hide your talents, but use them to produce something good.) That's about as obvious as "Buy low, sell high", IMO, but do you really believe that "buy low/sell high", or "it's better to invest than to hoard" would not be true if God didn't exist?
What's so remarkable about a set of teachings that merely restate the obvious?