And their objection to ID is? (Other than guilty by association.)
Evolution says nothing about whether a god or gods exist or not.
"Evolution", in the broader non-technical sense that it's often used, allows the universe to be godless, which to many is the same thing. That's where I think ID comes into play. In the big scheme of things, it doesn't contradict evolution. What it does is to provide a formal way of presenting the possibilty that the universe is not godless to students without delving into any particular theology.
It's not scientific because it's not falsifiable. It could be falsifiable if some characteristics of the designer were hypothesized, but this is scrupulously avoided, mainly because the whole motivation for the ID movement has nothing to do with science, but rather with inserting itself into public schools, which it couldn't do if the designer's characteristics were specified. However, if ID'ers were truly interested in formulating a testable hypothesis, they could hypothesize that certain features of life are designed, and if that's the case, then the designer could not or would not do X, where X can be any potential observation. If X were actually observed, then ID would be shown to be false, or at least that particular ID hypothesis would.
The reason that ID in general cannot be testable, however, is that for ID to be held seriously, X must be something that is not observed. Therefore, ID must be found to be consistent with all known observations. However, evolution is also consistent with all known observations. Therefore, ID and evolution would predict the same things, at least with regard to known observations. If ID'ers want to go out on a limb and predict something that evolution doesn't, then maybe ID can be taken seriously as science. That seems pretty unlikely, however. I will admit that, in part, ID'ers now might have a testable hypothesis, but it's not the one that they want. ID'ers, as far as I can tell, seem to make several related, but distinct claims. Namely:
1. There exists some feature in biological systems. This claim is obviously testable, and in most cases is not disputed by non-ID'ers.
2. The feature referred to in claim 1 could not possibly have formed via evolution. This is also a testable claim. To falsify it, an evolutionary mechanism must be put forth. I have yet to hear a claim of this type that hasn't actually been falsified.
3. The first two claims taken together imply that life must have been designed. This is the claim that is untestable. It's possible, after all, that there is some other natural process other than evolution that could have produced the feature in question without the need for a designer. You would have to find an observation that conclusively proves that some natural explanation is correct in order to falsify this claim. Conclusive proof of the truth of an explanation is impossible and not something that science ever claims. Therefore, falsifying this claim is not possible.