I'm with Twik here.
If I say I'm glad someone was re-elected because she's doing a good job, or oppose candidate X because I think his policies would be bad for the country, I hope people (with the possible exception of the candidate himself) can take that impersonally. If I said "anyone who votes for X is trying to destroy our way of life," I have to realize that people who voted for that candidate will take it personally.
Frankly, there are political positions I take personally. But I am willing to have that known, and let the chips fall where they may. After all, if I really think "that policy is both actively harmful, and hostile to me and people like me," what do I lose by saying that? If I'm lucky, the other person might see that and thinks "Hmm, Tea Drinker is a Purple, maybe I'm wrong about Purples." If, instead, they think "Oh dear, I didn't know Tea Drinker was one of those Purple people, I'm not inviting her to my party," and unfriends me, what have I lost, really? A casual acquaintanceship with someone who only wanted to socialize with me because they thought I was someone I'm not. (Somewhere in between, someone might think "Yes, candidate X supports this policy that Tea Drinker thinks is a threat to her, but I like their policy about these other things," and if they say so, then I get to decide how important the issue is to me in this case.)
I tend to agree. The reality is that it is extremely unlikely that any candidate who will do absolutely everything I would have them do in every circumstance. Even the candidate I support overall are never goldplated. For that reason, I don't take it personally if somebody else chooses to vote for the other guy who also has some flaws and a a few things to offer. If they rant about the fact that candidate A is the Antichrist I am a little turned off, however.
And on top of what Tea Drinker said, I tend to call my "friends" on the crap they say on FB the next time I see them in person. Not for disagreeing with me, but if they start the "Anybody who believes in X is unamerican, stupid, disgusting and destroying our way of life", then I will challenge them about it in person, and try to have a productive conversation about how hurtful it is to insult people like that. I expect better of my friends than that, & if they're not up to it, then we probably shouldn't be friends.
I'm actually have a similar issue with one of my roommates now. Let's say that we're both green believers, and he's dark green, whereas I'm more of a light-to-medium green. Lately he's been posting mocking things about red, blue, & yellow beliefs on facebook. I've responded (respectfully) both on his wall & in person, pointing out that, no matter what color our beliefs are, we should be trying to get along with people with other colored beliefs and not mocking them. The friendship may eventually fall apart, which is sad on one hand, but OTOH I don't want to live with, or share my life with someone who thinks it's ok to mock other people.