For the most part, Creationists just haven't taken the time to open a science book. Most have the audacity to claim that Evolution is just a "theory". Which, ironically, they are right. If they actually knew what a scientific theory is, then they would understand that a theory is not the same thing as a guess.
A scientific theory summarizes a hypothesis or group of hypotheses that have been supported with repeated testing. A theory is valid as long as there is no evidence to dispute it; so theoretically, it is possible to dispute a theory if you are able to disprove the hypothesis or group of hypotheses with real observations.
So the creationist should first find evidence that disproves the evolution theory before they can make any claim that Evolution is false. What creationists must understand that in order to disprove Evolution, they have to disprove countless of tested hypothesis that support Evolution.
Creationism doesn't have real science (evidence) to support it, its just a collection of guesses that are fueled by old superstitions.To this day the Creationist hypothesis has not ben awarded the title of a scientific theory. Evolution is a theory, creationism is not; its just a belief. Faith, by it's definition, means to accept something as true without proof. That is where Science and Faith stand divided.
I read great analogy that can further explain to you what a theory is:
Hypothesis: All swans must be white.
Observation: Every swan I've ever seen is white.
Test: A random sampling of swans from each continent where swans are indigenous produces only white swans.
Publication: "My global research has indicated that swans are always white, wherever they are observed."
Verification: Every swan any other scientist has ever observed in any country has always been white.
Theory: All swans are white.