“A third reason why we should love our enemies is that love is the only force capable of transforming an enemy into a friend. We never get rid of an enemy by meeting hate with hate; we get rid of an enemy by getting rid of enmity. By its very nature, love creates and builds up. Love transforms with redemptive power.”

1950s, Loving Your Enemies (Christmas 1957)
Context: A third reason why we should love our enemies is that love is the only force capable of transforming an enemy into a friend. We never get rid of an enemy by meeting hate with hate; we get rid of an enemy by getting rid of enmity. By its very nature, love creates and builds up. Love transforms with redemptive power.

1950s, What Desires Are Politically Important? (1950)
Context: We love those who hate our enemies, and if we had no enemies there would be very few people whom we should love.
All this, however, is only true so long as we are concerned solely with attitudes towards other human beings. You might regard the soil as your enemy because it yields reluctantly a niggardly subsistence. You might regard Mother Nature in general as your enemy, and envisage human life as a struggle to get the better of Mother Nature. If men viewed life in this way, cooperation of the whole human race would become easy. And men could easily be brought to view life in this way if schools, newspapers, and politicians devoted themselves to this end. But schools are out to teach patriotism; newspapers are out to stir up excitement; and politicians are out to get re-elected. None of the three, therefore, can do anything towards saving the human race from reciprocal suicide.

1950s, Loving Your Enemies (November 1957)

1950s, Loving Your Enemies (Christmas 1957)
Context: Another reason why we must love our enemies is that hate scars the soul and distorts the personality. Mindful that hate is an evil and dangerous force, we too often think of what it does to the person hated. This is understandable, for hate bring irreparable damage to its victims. We have seen its ugly consequences in the ignominious deaths brought to six million Jews by a hate-obsessed madman named Hitler, in the unspeakable violence inflicted upon Negroes by blood-thirsty mobs, in the dark horrors of war, and in the terrible indignities and injustices perpetrated against millions of God's children by unconscionable oppressors.
But there is another side which we must never overlook. Hate is just as injurious to the person who hates. Like an unchecked cancer, hate corrodes the personality and eats away its vital unity. Hate destroys a man's sense of values and his objectivity. It causes him to describe the beautiful as ugly and the ugly as beautiful, and to confuse the true with the false and the false with the true.

1950s, Loving Your Enemies (November 1957)
Context: There’s another reason why you should love your enemies, and that is because hate distorts the personality of the hater. We usually think of what hate does for the individual hated or the individuals hated or the groups hated. But it is even more tragic, it is even more ruinous and injurious to the individual who hates. You just begin hating somebody, and you will begin to do irrational things. You can’t see straight when you hate. You can’t walk straight when you hate. You can’t stand upright. Your vision is distorted. There is nothing more tragic than to see an individual whose heart is filled with hate. He comes to the point that he becomes a pathological case. For the person who hates, you can stand up and see a person and that person can be beautiful, and you will call them ugly. For the person who hates, the beautiful becomes ugly and the ugly becomes beautiful. For the person who hates, the good becomes bad and the bad becomes good. For the person who hates, the true becomes false and the false becomes true. That’s what hate does. You can’t see right. The symbol of objectivity is lost. Hate destroys the very structure of the personality of the hater. [... ] when you start hating anybody, it destroys the very center of your creative response to life and the universe; so love everybody. Hate at any point is a cancer that gnaws away at the very vital center of your life and your existence. It is like eroding acid that eats away the best and the objective center of your life. So Jesus says love, because hate destroys the hater as well as the hated.

Lessons of Dr. Martin Luther King, Jr. (1990)

Buddhist Socteriological Ethics: A Study of the Buddha’s Central Teachings (1999)