As Dr. Martin Luther King Jr. preached on a Sunday morning in 1957, he fought the temptation to retaliate against a society steeped in racism.

“How do you go about loving your enemies?” he asked the Dexter Avenue Baptist congregation in Montgomery, Alabama. “Begin with yourself. . . . When the opportunity presents itself for you to defeat your enemy, that is the time which you must not do it.”

Quoting from the words of Jesus, King said: “Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you .…