It's cognitive dissonance. A friend who minored is psychology has explained it pretty well to me when discussing people like the'rang-atang here.
Same for people who believe in a flat earth, or that dinosaurs never existed. These people probably know deep down that they are wrong, at least on some level. But their opinion is being formed for them by the people or communities around them. It's sad really.
It's also sad, because there are probably people around him that he is ruining relationships with. People who don't conform to his ideas, people who he has pushed away. I know I have people like that in my life I've had to push away. Because I cannot tolerate their hate. Their hate for science, their hate for other races, their hate for other sides, sexualites, or other ideals.
It's a shame that people walk through this world so blind, with access to the knowledge so readily available, and the facts almost always easily obtainable. This sort of ideology isn't even that, because it's not formed by opinion, it's formed by the lack of, or the complete disregard for facts.