I'm a Nice Fellow
Never let it be said that I let politics get in the way of human kindness. Of course I held the door for them so they could get in easily. Why should it matter what their politics were (in any event, who's to say they held leftist views in the first place)? I do wonder, however, what would have happened if I had've been wearing a "Support our Troops" shirt and a socialist fanatic was holding the door. Some of those folks can get pretty nasty.
Oddly enough, I find that I'm friends with a number of leftist individuals who write for my university's student newspaper. In most of these cases, I'm just following through with my friendly nature - you might think someone's political views are more or less the result of reverse-coprophagy, but you'll feel a lot better about yourself (and a lot less irritated) if you hold the moral high ground of being respectful. In one particularly interesting case, a fellow I've known for quite some time holds the most appalling leftist views - of course, being the son of a CBC employee and an "alternative-newspaper" publisher, this comes to me as no surprise. Conversely, he probably harbours similar thoughts about myself, albeit from an opposite point of view. However, we both get along outstandingly well, because we acknowledge that our political views are only part of who we are, and not the whole of who we are.
There is a lesson to take from this - don't let the fact that you abhor someone's political views cause you to treat them poorly.
After all, why settle on hating someone over politics when there's a million other reasons to think they're a jerk?