I am a Christian and I believe in the literal truth of the Bible (at least as original revealed), and I agree that creationism is killing the Republicans among moderate voters.
If I write a virtual reality computer program and hook up young children to it from birth, they would not be able to inductively take measurements from inside the program and induce the computer code that made the program. They would only be able to induce how the physics engine works.
The same principle applies to the universe. We can not induce God's plan.
The problem with Creationism is not that it isn't true, or it could never be true. It may very well be. In fact creationism and evolution are not mutually exclusive either, I don't know why people fight over it. If in fact we were created then the Creator may have programmed us to evolve and better adapt ourselves to our environement as it keeps changing.
The problem with the creationist approach in the scientific community is that it stops abruptly with God/Creator and provides no explanation beyond that. You might argue that its a matter of faith but that argument does not hold water with scientists. There is no rational explanation for who/what it is, how it came into existence, why its there, why it creates, destroys..etc and not to forget the countless inconsistencies and self defeating arguments that follow if you go down that path. Scientists don't like that.