It’s not a modern standards thing, Genghis Khan was seen as a complete monster in his own time.

The claim is “Earth isn’t a planet”, sometimes with the addition of “space isn’t real”.

“Why” implies they act according to some form of logic. The thing is, they’re racists, and racists tend to be fucking stupid.

It should be legal to slash the tires of anyone who does this.

Somewhat pedantically speaking, the belief that an evil god exists (exclusively or otherwise) is dystheism. Misotheism is the hatred of a god or gods. Dystheism implies misotheism, but they’re not exactly the same.