85% of Americans either completely deny evolution or they think supernatural magic is a mechanism of evolution. Why does this epidemic of breathtaking stupidity matter?

The question is answered at What's the Matter With Creationism?

Why does it matter that almost half the country rejects the overwhelming evidence of evolution, with or without the hand of God? After all, Americans are famously ignorant of many things—like where Iran is or when World War II took place—and we are still here. One reason is that rejecting evolution expresses more than an inability to think critically; it relies on a fundamentally paranoid worldview. Think what the world would have to be like for evolution to be false. Almost every scientist on earth would have to be engaged in a fraud so complex and extensive it involved every field from archaeology, paleontology, geology and genetics to biology, chemistry and physics. And yet this massive concatenation of lies and delusion is so full of obvious holes that a pastor with a Bible-college degree or a homeschooling parent with no degree at all can see right through it.