Hey, I was a physics major half way through Harvard before I changed my mind, and I have a fair understanding both of the scientific method and the history of science.
For the most part, creationism was just a backdoor way of talking about religion as if it were science. But I don't really blame the creationists for doing it; it was a result of their frustration at a series of unconstitutional court decisions that violated the freedom of religion clause.
Intelligent design theory, on the other hand, includes a good deal of scientific argument. No doubt it also has hangers on who wouldn't know science from a hole in the ground, but you really can't blame that on writers like Behe.
Darwin is the one I have trouble with as a scientist. For one thing, his argument is circular. For another, he was a racist. It wasn't just T.H. Huxley and the cultural evolutionists who were responsible for the rise of racism and eugenics in the nineteenth century. It was also Darwin himself.
The full title of his original book, which contains quite a number of racist passages, was this: "On the Origin of Species by means of natural selection: Or the preservation of favoured races in the struggle for life."
I've read several of his essays on irreducible complexity, and find the argument persuasive. It's not definitive, but it is an overwhelming argument statistically, and that's all that's really possible.