If a friend or relative makes a racist or homophobic remark, do you tend to confront them or let it slide? Are you more likely to confront them if it offends you directly or someone else who seems reluctant to speak up?
I confront them. With varying results, but that's not the point. The point is that if you don't confront them, they think you're agreeing with them.
It's not easy, but it's necessary.