Evolution should be taught in science classes because its based on scientific knowledge about biology, chemistry, and physics.
Creationism should be taught in history class because its based on some 2000+ year old text that has not one inkling of anything that could be called scientific in it. It is a creation myth based on people with no knowledge of how the world really worked. All peoples have creation myths, just because its from the bible doesnt make it anymore relevant then anyone elses creation myths. Some are based on a snake giving birth to the world, some are based on birds, etc. Its just a story.
Creationism is not a theory, its history and should be taught as such.
To me believing in creationism would be like me still believing in santa claus.