A lot of the problem with Creationism and it's spin-off ID is that they truly believe that it had to happen that way. That mankind came from two naked people in a garden who got tricked by a talking snake. That's where original sin comes from and requires Jesus to sacrifice himself. It's the foundation of their house of cards. Plus if you question it, you have to question the rest of it as well.
It's also the source of their bizarre attacks on Evolution because they're convinced that if one thing is wrong, the whole theory must be tossed out instead of looking into that one area. Usually these attacks are on areas that scientists figured out and tossed out anyway, like Piltdown man. No one teaches it except as an example of a hoax and how the scientific method is used to figure out what's real and what's not.