No teaching of our Lord’s has been more attacked, slandered, ridiculed, and vilified than His calling on people to love those who hate them.

Source: The Most Revolutionary, World-Changing Thing Jesus Ever Said – Joe McKeever Christian Blog

Luke 6:27-36 The Message (MSG)
^27-30 “To you who are ready for the truth, I say this: Love your enemies. Let them bring out the best in you, not the worst. When someone gives you a hard time, respond with the energies of prayer for that person. If someone slaps you in the face, stand there and take it. If someone grabs your shirt, giftwrap your best coat and make a present of it. If someone takes unfair advantage of you, use the occasion to practice the servant life. No more tit-for-tat stuff. Live generously.
^31-34 “Here is a simple rule of thumb for behavior: Ask yourself what you want people to do for you; then grab the initiative and do it for them! If you only love the lovable, do you expect a pat on the back? Run-of-the-mill sinners do that. If you only help those who help you, do you expect a medal? Garden-variety sinners do that. If you only give for what you hope to get out of it, do you think that’s charity? The stingiest of pawnbrokers does that.
^35-36 “I tell you, love your enemies. Help and give without expecting a return. You’ll never—I promise—regret it. Live out this God-created identity the way our Father lives toward us, generously and graciously, even when we’re at our worst. Our Father is kind; you be kind.