The problem with that issue is that many creationist/IDers either don't understand the facts or don't want to believe the facts so it is hopeless to argue with them.
Actually, I think they dislike the results of evolutionary theory.
Yes, you are right. If their concept of God based on literal Scripture is perturbed in any way, then it is the perterbation (i.e. the real world) that is wrong. The Bible says so.