The reason why cult beliefs are considered mental illness is that most people don't understand psychiatric guidelines. Psychiatrists are not supposed to discriminate against patients for their cultural beliefs, and if they do, you can sue them for malpractice. Unfortunately, average joes aren't held to any psychiatric standard and can do whatever they want, and what some of them want is to discriminate against people different than themselves. If we want to change that, we need to take action to change that by telling cult haters to fuck off.