I notice there are whole some theists that lie about atheists, what it means to be an atheist, what atheists believe in, etc...

And of course they will jump through hoops to justify their lies (Bodhiharta comes to mind. Bodhiharta will lie about about anything, so it's not surprising), Or just ignore any retort (Nonbobblehead).

It always bugged me as to why would these people be so dishonest to others.
Then (The afformentioned) bodhiharta (Hence known as "bod") said:

Guilt is not good for survival.

That's it! They don't want to feel guilty.
"aww gee, it would be horrible for this guy to burn in hell forever, but he's an atheist, and atheists are god-hating-baby-raping-idiots"

Of course I think this goes deeper.
"If I feel sorry for someone in hell, then there might be something wrong with hell, and therefore a problem with god's plan, and then god. doubt will follow, and then, I will against god, and that will make me evil... etc.

I really doubt most people like the two people mentioned above would have thought of atheists as evil-bigots until this idea was brought up (Maybe externally).