A perceived reason
"Any republican who acts the same way must be instantly vilified as evil "
Because IN GENERAL (I love escape hatches), Republicans are associated with do less for other people not in their immediate community, keep their money, and maintain an isolationist community viewpoint. Unless of course they are spreading the word of Jesus.
Democrats are associated with taxing other people, using that money to fund some possibly worthwhile stuff, but doing it wrong (even if the stuff was needed), and the vast majority of money is simply wasted.
So, Republicans see Democrats as simply stupid, not evil, at least until the tax man comes with a gun to take your stuff. It is assumed that their stupidity is obvious, because they vote for politicians that are obviously immoral and corrupt. Like Slick Willie. Of course, those that oppose the word of Jesus are assumed to either be ignorant or evil, and if not converted must be killed. Ok, maybe a bit of paranoia there. But not enough based on the real possibility of violent attack.
Democrats, on the other hand, can easily pick out the rantings of whatever Republican is on CNN, playing to their local base, getting into war cry mode, and ascribe it to evil (lower case e) intentions. And lets face it, a lot of people have suffered due to one of the few capital Evils around, ie: Cheney, who is one of the main Republican standard bearers for the moment. And of course, let's not forget that violent attack the religious people are prone to do.
Bottom line, Republicans are losing, and it is simply demographics. They are dying off, too few people are joining up, and their message doesn't seem to work.
Oh well. You better push your alternative party hard, or become an active Democrat if you want to have a say in the political future.