You're sure they're wrong, but listen anyway.
You'll discover more about them by listening to them unburden their soul. And maybe they will learn more about themselves as well. We often learn what's inside of us, who we really are, when someone opens the door to letting us open up.
If you don't understand, ask clarifying questions, not to cross-examine them, but to open the door further, to shed more light, to see more details of what they care about, how they see the world.
Exert your strength through generosity. Give them the space to bloom, to open up and show you the beauty that God has planted within them.
At the end of it all, maybe you'll be just as convinced of how wrong they are. But hopefully you'll understand more of why they believe and think and act the way they do.
Maybe you'll never see eye to eye with them on these matters. But knowing someone on the other side, someone you know as a person and not just an anonymous slur, will enrich your soul. And if you are challenged by the person and ideas you encounter, perhaps through the process you will be stronger, and just that much more aligned with what is, just that much more deeply rooted in the Truth.