Both what? Why should they teach creationism?
Evolution is faith too.
If by "faith" you mean "we can't be 100% sure" then, I guess, yes. But I suppose you don't want relativity or the nature of the atom taught either. They are both theories.
They don't run in the same evidentiary vein as Evolution or the Big Bang. Creation Science and Evolutionary Science are both on the same footing when it comes to who was where to see what when as far as the origin of life and matter. One theory can be more scientifically evidential than another based on quality and quantity of evidence but neither is anything more than a basic assumption and a lense through which the facts are viewed.