This is how we know what love is: Jesus Christ laid down his life for us. And we ought to lay down our lives for our brothers and sisters.

This is actually 1 John 3:16 (from the letters of John). John 3:16 (from the gospel according to) is actually:

For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.

(Arguably the most famous new testament quote besides “Jesus wept”.)