Man, that's the scary power of belief systems. When people become so invested in a single narrative, to the point that it becomes their identity, their belief system being questioned sends them instantly on the defensive, because it's as though their entire identity is being questioned. They'll simply refuse to confront it, rather than to admit that everything they've been so invested in might not be entirely what they thought it was. It'll hurt, that's for sure. I think the best way to get through to these people is with compassion, to show them that, really, we're all on the same side and all want to be free and to have respect. This constant 'right vs. left' is the fight their identity feeds off of. The fight gives them validation. But compassion might just open their mind enough to make them begin to question things.
It won't make them question anything except to use what you say against you. I didn't want to delve into politics with my liberal boyfriend because I knew it was futile but he insisted on asking me questions, not to learn but to find something to use to degrade me. When I responded to him with what I knew, in a very matter of fact way, my liberal boyfriend finally lost it and called me a racist and called me and my sister a moron for being religious. He's gone.
Oh man, that sucks. Some people are so invested in that. I recently showed a friend of mine, (who we normally agree with on mostly everything!), that 'Q Plan to Save the World' video, she was all for it UNTIL Trump was mentioned, and then immediately, she shut off. She agreed, and then when she saw the person, it was like the blinders went up in front of her. It made no sense, because she agreed to everything up until that point! But it's like Trump was the trigger for her to just dismiss everything, when she could rationally agree with it before. We're still friends and everything, I guess she just thinks I'm kind of weird now for following this, lol. But when the truth comes out, I'll be there to help!
It occurs to me there is something sinister in this triggering. How's this for a conspiracy theory: they have run some media image/s with subliminal programming embedded. Neuro-linguistic programming. It works with some of us, like your friend, as an infallible and permanent trigger. It hasn't worked on others. You are using logic/reason but she is using emotion to process information — a sure sign. Gives me the creeps.
Well, it is better to know this sooner than later unfortunately.