Hm, is the poster one of my ex-BFs? He was on the far left side of the political spectrum, and denounced most people who didn't agree with him as a right-wing lunatics (yet he got upset when I suggested that he just might be a left-wing lunatic). I'm not exactly conservative, but he told me on a few occasions that I had been brainwashed by my Limbaugh-worshipping father, and wasn't that a shame! He was unable to carry on a conversation of any length without getting all worked up about the evils of the Bushes and Reagan, which got old really quickly.
He told me that he had quit multiple bands whose members were big fans of the Bushes and Reagan and reminded him constantly of it during rehearsal. I have my doubts about this and suspect it was more like one of them said one complimentary thing about a Republican, which he blew out of proportion, went on a tirade, then stormed out.
As someone mentioned above, it's nice to be on the same page with bandmates when it comes to social and political issues. However, where I live it's hard to find good musicians regardless of their political affiliations. I've found that it's best just to stay away from discussing those things as much as possible. Bands have enough drama without throwing politics into the mix!