Sure, theory like big bang and theory of relativity cannot be tested in such a fashion. However there are schematic models with each, and observations based on other theories. None of those theories, creationism, intelligent design are reliant on such models. Unless it's brought to the next level and start to prove the hypothesis that this is the responsiblity of a creator. I don't discount it as an idea, although the little I know about creationism it doesn't really have any scientific basis. It could very well be proven true in time like many others.

I'm not an atheist by any means, so don't get this impression I don't believe in god. I believe in concepts like reincarnation and enlightenment. That doesn't mean it's fact, I simply believe in it. Nor does it imply it shouldn't be taught in schools, I simply think it shouldn't be intermingled with science until some of the hypothesis they state are started to be tested and proven true.