While it's superficially comforting to imagine that evangelicals are somehow "missing the point" of Christian mythology, the hard fact is that they are actually more consistent than those who attempt to straddle the divide between reality-based actions and belief-based behaviors.
It is more intellectually coherent to believe that an invisible magical creature created the universe than to adopt the intellectually incoherent position of accepting evolution, with all its stochastic elements, while still believing in (evolutionarily impossible) magical creatures under whose guidance some divine plan inexorably unfolds. The fact that evangelicals are in general low-IQ and display atavistic behaviors is of course embarrassing, but it's no more than one would expect. Intellectually limited people seek simple-minded answers, while also being incapable of adequately processing real-world information. As such they find the real world perpetually threatening, and thus pre-emptively adopt positions they imagine to be "protective." This is merely one of many reasons why any society aspiring to basic civilized norms and humane behaviors can't afford to tolerate religionism in any form whatsoever.