From the New York Times bestselling author of Misquoting Jesus comes a surprising history of Jesus’ most radical commandment, tracing how this extraordinary duty to love even those who are strangers to us has shaped our world and our lives.

From the earliest of times up through Greek and Roman antiquity, moral thinkers prioritized generosity toward friends and family. Even Old Testament exhortations to love your neighbor said little about the suffering of those beyond your own community.

Jesus changed all this, introducing a revolutionary new ethical obligation to show love to those you don’t know, and might even dislike, through acts of care. The implications of this radical commandment would be debated, misunderstood, and resisted by early Christians. But by the 5th century, this new “common sense” began to transform the moral conscience—and the politics—of the West.

In Love Thy Stranger, New Testament historian Bart D. Ehrman charts the causes and consequences of this ethical revolution up to the present day with his signature sly humor and verve. For in this moment of renewed debate over the limits of the love we owe to others, Jesus’ most demanding commandment remains quite provocative, even two millennia on.