To add to this;
It's not always what you say, but how you say it.
Be respect and nice, and even if you never change their opinion, that's OK they are entitled to it.

Of course people are biased though, and they should be.
Bias is part of the systems that help keep us safe and you know, not dead. Yeah, it's not always needed, but I'm not sure how possible a truly unbiased person is without complete apathy. Everyone has their opinions.

Example: I am biased against the person who threw sand in my eyes and kicked me in the crotch. If they get kicked in the crotch I sure as shit won't be running to their rescue. My bias in this situation helps me because if I avoid them or they get kicked out of school, I don't have to deal with them kicking me in the crotch again.
Thus, my crotch is safe from being kicked for another day!(This is all hypothetical btw, it has not actually happened, haha.)
10 years later I still don't like them, only to find out they're in jail for murder. Good choice? I think so. They still sound dangerous. I don't want to get murdered or kicked in the crotch, ok? So I am just going to keep staying the hell away from them.

Yes, people and unchanging opinions and bias can be difficult to deal with, but, they're not trying to be malicious about it I don't think, they just happen to think their way is right...why don't you change YOUR opinion? Know what I mean? lol