Tied in with willful or just old-fashioned dumb ignorance, I think, is an inability to recognize satire. I just ran across an article about a school district in Missouri (NOT Texas, mind you - for once)that has banned
Slaughterhouse-Five from its campuses.
The Neverending Campaign to Ban 'Slaughterhouse Five' - The Atlantic
I grew up a hundred miles or so from Republic, and I am very confident that the school board is loaded with the denialists you are speaking of. And I will bet the rent none of them have read any Vonnegut at all, and are proud of it.