The biggest mystery that remains for me is who came up with some of the social and moral philosophy that we find in the New Testament. ‘Love your neighbour as yourself’, ‘do to others as you would have them do to you,’ ‘love your enemies,’ all pretty profound ideas. If Jesus didn’t exist, who came up with this stuff, and where did it originate?Since then I've been reading about 'The Golden Rule' - basically the ethic of reciprocity, or rather, the idea that one should treat others as one would like others to treat oneself.
It turns out that this idea exists in pretty much all major religions and philosophical traditions. I'll give a few examples.
In Ancient Greece;
"Do not to your neighbor what you would take ill from him." - Pittacus
"What you do not want to happen to you, do not do it yourself either. " - Sextus the Pythagorean.In China;
"Regard your neighbor's gain as your own gain, and your neighbor's loss as your own loss." - LaoziIn Judaism;
You shall not take vengeance or bear a grudge against your kinsfolk. Love your neighbor as yourself: I am the LORD. - Leviticus 19:18In Islam;
A Bedouin came to the prophet, grabbed the stirrup of his camel and said: O the messenger of God! Teach me something to go to heaven with it. Prophet said: “As you would have people do to you, do to them; and what you dislike to be done to you, don't do to them. Now let the stirrup go! [This maxim is enough for you; go and act in accordance with it!]” - Kitab al-Kafi,Myriad other examples can be found on the Wikipedia page - http://en.wikipedia.org/wiki/The_Golden_Rule
So, far from being a mystery, it turns out that the concept has always been fairly common across all human cultures. In fact, I'm now starting to think that the idea is probably more or less innate to all human beings.