Why do certain people hate atheists?

[MrScorpio]

19. To the Atheist haters, Atheism creates the possibility that their faith may be for naught

Faith in something that they can't readily see is at the center of belief, Atheism is a rejection of this faith basis.
Believers base their entire moral worldview on that basis of belief as well, thus to the believers, it means that it's rejection of the believer's self-identification as a moral person.

One's goodness and morality is based in a belief in a higher power, the Atheist rejects the belief system, this tells the believer that the Atheists considers them conversely evil.

Then there's the likelihood of the idea of Atheism catching on. If enough believers reject their belief, it could weaken the existing social and political power base. It's a numbers thing.

Fear of Atheism's impact is at the heart of the issue.

They're afraid that Atheists will someday win.