You claim "For complete strangers, it's one thing; I can decide their opinions are irrelevant and tell them to fuck off. But if it's someone I like/respect, or if it's a common view in a place where I'm otherwise comfortable hanging out, it's difficult to keep listening to"... I doubt that the people you debate with here at the BBS, or the people you screencap and post on FB are people you like/respect
You forgot that one part *immediately after* where I said:

But if it's someone I like/respect, or if it's a common view in a place where I'm otherwise comfortable hanging out
I like hanging out here, because it's one of the first forums I really started posting in regularly back in 2008, and I know a lot of the people here on FB and elsewhere. And yet, I've noticed we seem to get a lot of libertarian assholes who think every crime is punishable by death or life imprisonment, or who think that right to property is more important than right to life. I used to just kind of ignore them (in fact, I never posted in politics until a year or so after I started posting here), just because I wanted to avoid ruffling any feathers. The same goes for the FB groups I frequent --- at first I would just hang around and offer my occasional meager comment, but after seeing mountains of stupid people making indefensible/racist/sexist/religiously-bigoted comments, I just get tired of hearing it.

but I often stay out of conversations with you and have taken to avoid responding when I disagree, BECAUSE you get incredibly condescending and "I'm right; you're wrong" about it. You complain about other people trying to be superior, but that's in fact the same thing you do.
I feel more that an overwhelming majority of our political discussions are founded on you fundamentally misunderstanding what I'm saying. I can't count the number of times you've left a political comment on something I wrote that seemed to completely miss the point/not get the joke, and I had to explain what I really meant by it -- like one time I posted this political joke about foodservice workers not taking unpaid sick leave because they need the money (and it had the caption, "oh, look, our food is here!"), and you went on this rant about how people can take off sick if they want, when the point was that they don't get paid for taking off sick (and that their wages aren't very high to begin with). I really don't mean to be condescending, but sometimes I just feel like you're missing a really obvious point. Before I learned you were an English teacher, I used to wonder if there was some language barrier that I wasn't considering, that was making my comments harder for you to understand.

Anyway, when discussing issues that are a matter of factual basis, someone is right and someone is wrong. I don't see anything condescending or arrogant about pointing that out. A lot of people I know seem to have this fundamental issue with facts existing, and with knowledge being affirmable; if someone says, "I don't believe in biological science," for instance, and I say, "well, you're wrong, because the only reason I'm alive today is because biological science works and is a legitimate field," would that be condescending? Or should I take care to consider his or her feelings and make sure they don't feel invalidated by the fact that they are wrong?

I mean, if it's a really minor issue, I can understanding feeling overwhelmed if someone's being overly aggressive about it. But when we're discussing factual matters, how is it "condescending" to just state facts?

If what you're saying is true - that you don't like talking about politics - then basically your entire goal in getting into these long-winded debates is to prove other people wrong and you right, which is kind of obnoxious and very arrogant.
Well technically, my goal is (as I said):

and so I say things and ask questions in a precise, incisive manner --- not to change his/her mind or persuade him/her of my position, but to demonstrate to the world what a fucking nimrod they are, and how baseless their righteous self-confidence is.
Maybe it's just because I live in an IRL environment where, everywhere I go, everyone I meet (with a few very rare exceptions) is in complete opposition with everything I believe about everything --- the population of my neighborhood, my city, and my general area is very anti-science, anti-woman, pro-religion, pro-gun, Republican/libertarian, "the civil war ain't over yet, it's just half time" type of people. And so I've gotten very good at hiding my opinions about things, and I only really bring them up IRL if I feel like I'm being pushed into a corner, or someone is just really not letting it go. But every now and then, I just get this feeling like I am the only person in this entire state that is not a gun-toting, government-hating, science-denying asshole, and so I guess there's this hope deep down that, if I put this idiot in his/her place, then someone will see it and think, "hey, there are other people like me! I'm not crazy!"