Personally? Propaganda.

Take flat earth people for an instance. They maintain that the round earth is a concept which invalidates the bible. Such a thing doesn't even register in the average christian's brain. It's simply not a challenge to their beliefs in any way. However, someone can be born into a flat earth cult and be indoctrinated since birth, or fall into such cults and convince themselves that basic astronomy is a war against Christendom itself.

With LGBTQ+ people you have a fertile ground for hateful propaganda. It's centuries old and public opinion on even the most innoffensive gay white liberal person changed massively in just a few decades. But I maintain that people have to be mobilized to hate trans people - a concept that a lot of older people can some times barely understand - and ALSO to make it a core to their entire personality. Which is why anti-trans politicians are always on the lookout for ways to make it a relatable issue, like with fairness in sports.