Science is the systematic method of explaining natural phenomena observed either directly or indirectly. Anything that is non-naturalistic, not tentative, and unfalsifiable is not science. Therfore, creationism is not science.
from Merriam Webster's dictionary: Science- the state of knowing...2) a department of systemized knowledge as an object of study< the science of theology>. there is a natural science defintion which deals with the physical world but that is just one of the meanings and of course doesn't exclude a wide variety of scientific study including creationism. This is obvious and shouldn't even need to be stated.