The theory of intelligent design is not only not falsifiable; there is simply no way to test it. But that is not the main reason it is not science. The main reason is, that ID does not actually explain anything. When we ask, "Why is the world the way it is?" it answers, "Because it was designed that way." The world is the way it is because it is that way. That might be the furthest from a useful, satisfactory explanation you can get.
String theory has problems, too. But while intelligent design is untestable in principle, string theory is just really hard. It is quite possible some clever scientist will devise a way to test it.
That's some major leage convoluted logic.
I still don't know why people aren't free to reach their own conclusions about our origins.
OR
LOL!