“We must meet hate with love. We must meet physical force with soul force.”

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.

2014, Address to European Youth (March 2014)
Context: In the end, the success of our ideals comes down to us -- including the example of our own lives, our own societies. We know that there will always be intolerance. But instead of fearing the immigrant, we can welcome him. We can insist on policies that benefit the many, not just the few; that an age of globalization and dizzying change opens the door of opportunity to the marginalized, and not just a privileged few. Instead of targeting our gay and lesbian brothers and sisters, we can use our laws to protect their rights. Instead of defining ourselves in opposition to others, we can affirm the aspirations that we hold in common. That’s what will make America strong. That’s what will make Europe strong. That’s what makes us who we are. And just as we meet our responsibilities as individuals, we must be prepared to meet them as nations. Because we live in a world in which our ideals are going to be challenged again and again by forces that would drag us back into conflict or corruption. We can’t count on others to rise to meet those tests.

1950s, Loving Your Enemies (Christmas 1957)

1950s, Loving Your Enemies (November 1957)
Context: Somewhere somebody must have some sense. Men must see that force begets force, hate begets hate, toughness begets toughness. And it is all a descending spiral, ultimately ending in destruction for all and everybody. Somebody must have sense enough and morality enough to cut off the chain of hate and the chain of evil in the universe. And you do that by love.

Quoted in "The Civilizing Mission: A History of the Italo-Ethiopian War of 1935-1936" - Page 172 - by A. J. Barker - 1968

1960s, Address to Cornell College (1962)

Source: "Azerbaijani Leader, Restored To Power, Imposes Emergency Rule" in The Washington Post https://webcache.googleusercontent.com/search?q=cache:epcCRJyvH3AJ:https://www.washingtonpost.com/archive/politics/1992/05/15/azerbaijani-leader-restored-to-power-imposes-emergency-rule/c4a5d291-a743-4227-90db-54e0f9739b80/+&cd=3&hl=en&ct=clnk&gl=us (15 May 1992)

1960s, The Rising Tide of Racial Consciousnes (1960)