Because creationism is not scientific.
Dur!
Why do you evolutionists make such stupid claims. Scientists were once creationist. Compare your theory to creation and tell me why your theory is more viable ?
A Theory of Biblical Creation
This makes absolutely no sense, as usual. There is nothing supernatural about the natural world. The rational (natural) world is explainable, understandable and knowable. We have no need for faith to understand that the force of gravity is relentlessly consistent across all of the universe we have discovered. For your enlightenment, gravity is both a fact and a theory. Over the last century, we even witnessed one theory of gravity (Newton's) as it was replaced by a newer, better theory of gravity (Einsteins). But the fact of gravity remained through the entire time period. Apples did not suspend themselves in mid-air waiting for the outcome.
Lets compare the concepts of theories using both evolution and gravity as compared to supernatural intervention. Both evolution and gravity assertions are theories. Both have aspects and elements missing (we don't have any idea what gravity even is, but we can obviously test for, examine and measure its existence. Both evolution and gravity require certain assumptions about their mechanisms. Both are "disproven" by biblical fiat-- in the holy texts, people rise to heaven in chariots, the sea separates, people walk on water-- all of these things are in direct opposition to the theories of gravity, precisely like evolution is in direct opposition to creationism. And finally neither the theory of gravity nor the theory of evolution makes any mention of gawds. None. That is not an assumption, neither says a thing about any gawd.
There is no difference between these two theories (other than mechanical ones) yet we never hear of "miraculism" being demanded as part of the syllabus in science classes because gravity defeats biblical stories. There is clearly a deeper concern, a broader agenda-- and I submit to you that evolution is so overwhelmingly presented and so difficult to dismantle, that most theists subconsciously fear that if it is true, their entire worldview is shattered. That is precisely why many creationists have such a visceral hatred for evolution and why they reel off into promoting these fantastic claims of the supernatural.