For a simple example: my mother is Catholic and until Trump came along, a lifelong single-issue Republican voter who always said she would be a Democrat if it weren't for abortion. She attends church in an extremely progressive, famously LGBTQ-friendly town.
There's a transwoman who attends her church (let's call her Rita). This lady is probably in her mid-50s to mid-60s and has been a fixture at the church for at least 5 years. My mom has been in choir and bible study groups with her for years now. She still just can't see Rita as a woman. Treats her politely but behind her back refuses to call her "she" and says she's a "man in a dress".
She's really offended that Rita uses the ladies' room. I've asked her why and she can't articulate it, she just feels like it's an invasion of her privacy, because men don't belong in the ladies' room. And when I point out that Rita isn't a man, she just rolls her eyes. I've asked her if she's worried that Rita is in there for predatory purposes and she admits that she doesn't think Rita intends any harm. I've asked her how she'd feel if she were forced to use the men's room and she says "but that's different!"
My mom prides herself in being a moral person, and still can't manage to get past her bigotry to see Rita as a woman. There are just too many mental blockades against it. But since she thinks she's so highly moral, she thinks she must be correct in this situation. It excuses her from finding empathy and bettering her attitude toward trans folks.
My longwinded point is that when people who consider themselves highly moral are bigoted, there's almost zero chance of getting through to them. And I think a lot of the people who are bigoted against trans folks feel that morality is on their side and being trans is morally deviant, so they think they're justified in their prejudice.
JG Hertzler as the illustrationist was delightful