When you hear of a devastating earthquake thousands of miles away, you might reach into your pockets to make a donation. That's the fault of an itinerant Jewish preacher from Palestine, then an obscure backwater of the Roman Empire, otherwise known as Jesus Christ.

Early Christians, like their fellow Roman citizens, had much in common with us: a good life was one in which you could provide for your family, care for your friends and contribute to your community. But Jesus brought about a moral revolution in the West, asserting you should love total strangers like you love your family. Of course this is easier said than done, and later generations of Christians would water such teachings right down. Yet public hospitals, orphanages, even government welfare, all owe something to the legacy of Jesus' distinctive teachings. As Christianity conquered the West, it changed what it meant to be a good person for all of us.