I have good friends who occupy the polar opposites of the political spectrum. They LOUDLY occupy those positions. I've no problem with this, and will gamely debate their stances on the topic-du-jour whenever I'm around them. I like being a sounding board/devils advocate in most debates.
The problem comes when these friends are at the same function (or posting polemics on Facebook). Both sides seek out support from me, and no matter what my personal feelings are on the subject, I always feel like I have to play Switzerland to try to keep everything civil.
I respect their passion for discussion, but sometimes wish I wasn't constantly put in the position of ref.