A scientific theory is "a well-substantiated explanation of some aspect of the natural world that can incorporate facts, LAWS, inferences, and tested hypotheses." (National Academy of Sciences)
"No amount of validation changes a theory into a law, which is a "descriptive generalization about nature". So when scientists talk about the theory of evolution--or the atomic theory or the theory of relativity, for that matter--they are not expressing reservations about its truth."
In addition to the theory of evolution, meaning the idea of descent with modification, one may also speak of the fact of evolution. The NAS defines a fact as "an observation that has been repeatedly confirmed and for all practical purposes is accepted as 'true.'" The fossil record and abundant other evidence testify that organisms have evolved through time.
Scientific American: 15 answers to creationist nonsense
Creationism is a collection of untested hypothesies, not yet a theory. This is still science and every hypothesis was once untested however many creationist "scientists" do not adhere to scientific method.
My Personal Opinion: As soon as the first non-christian scientist stands up and says "hey, i reckon the earth is pretty young" or "i don't believe in god but it seems like life popped up from nowhere". It might be worth a look into.
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