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 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. Bart D. Ehrman asserts Jesus’s moral revolution was both simple and impossible: you should love strangers as much as you love your family. And you should forgive those who wrong you freely. Most of us will never live up to these ideals. But much of the good we do comes from the fact we feel we ought.

By demanding we love, Jesus came to trouble our consciences, not to salve them.