A popular bumper sticker reads: "God says it, I believe it, that settles it." For most Christian fundamentalists, that statement neatly sums up their belief in Biblical inerrancy. They believe in creationism because the Bible says that Got created everything in six days at some point less than 10,000 years ago.
"Creation scientists" take that viewpoint a step further. By faith they begin with belief in creationism- then they search for evidence to back that belief.
True scientists study the evidence, drawing their conclusions from that evidence. Science does not deal in "truths," but in models which have predictive values. Evolution is a truly scientific model; it is open to examination and challenge. Over the years scientists have modified their evolutionary viewpoints to fit the latest evidence. Because it is Bible-based, creationists never modify their hypothesis, or even admit it could be in error.
Creationism is clearly based upon religion. AS such, teaching it in church, Sunday school, parochial school (or even in comparative religion classes in public school) is fine. However, because it is faith-based, teaching creationism as science in tax-supported public schools violates the separation between church and state.