In most cases avoid them. You can't fix stupid. Having said that, My best friend is a highly biased Baptist, homophobic, you name it, except racially biased individual. Call it Karma, I guess, but when her son fell in love with an African American woman and they had two children together, she accepted and loved the children and never considered their color. (The relationship didn't last, and she has problems with his ex, but racial issues aren't involved, just the usual "ex problems"..) I wonder what would have happened if another of her (3) sons had decided he was homosexual. Sometimes the problem fixes itself.
At work we tiptoe around the narrow-minded ones and try to steer clear of any conversation that might set them off. Usually our policy is to say nothing and walk away. If you handle it right, and apparently we are, they don't come after us. (Something like "I think I hear my phone ringing," or "Sorry, but the copier is available now, and I need to use it" usually works.)
There are times, however, when you just can't keep quiet. Recently when one of them was ranting about the evils of Obamacare, I told her that I voted for it and was glad it passed. When she asked why, I replied that my son now had insurance (she already knew that he has a potentially fatal pre-existing condition.) It looked like a light went off in her head and she said, "Oh." I've never heard another word from her about that. We are still on good terms.