He who passively accepts evil is as much involved in it as he who helps to perpetrate it. He who accepts evil without protesting against it is really cooperating with it. — Martin Luther King, Jr.
This is true but gosh it's tough to act on. It's one thing, for example, to behave fairly and justly to all people; but to go the extra step and decry the bigot (who may be an employer, or client or older relative) that's hard. I suppose knowing what we should do isn't everything - the challenge is actually doing what we should do.