Richard Neuhaus has an excellent little essay on the Intelligent Design/ Darwinism debate in the April issue of First Things. Here are a couple of paragraphs of an article that should be read in its entirety:
On the matter of taking into account all pertinent evidence and explanatory proposals one often hears the objection that if we are going to be fair in introducing alternative explanations into the classroom we will have to give time to a menagerie of ideas from pantheistic to animistic creation stories and everything in between. This is, of course, a transparently disingenuous attempt to justify continuing the monopoly enjoyed by the materialistic explanation.
The fact is there are not an indefinite number of alternative explanations which would have to be accommodated. There are precisely two genuine options in this debate. Life either arose by purely mindless, mechanistic processes, or it's appearance involved some degree of intelligent input. These two disjuncts exhaust all the possibilities. Nothing else need be discussed.
Nor is it correct to assert that one of these alternatives is a scientific hypothesis and the other is religious. They are both metaphysical explanations. Neither of them is ultimately provable or disprovable by any empirical test. If one is to be excluded they should both be excluded, if one is to be presented in public school classrooms they should both be presented in public school classrooms. There is no reason why the materialist theory should be privileged over it's competitor.
This is all that most people who are trying to get Intelligent Design acknowledged in high school biology classes are asking. They wish to see students genuinely challenged to think through the two contrasting theories and be allowed to decide for themselves which one best accounts for the evidence. Do living things show indications of having been intentionally designed or do they instead appear to have resulted from mindless, purposeless physical laws plus serendipity?
The guardians of the entrenched materialist orthodoxy know very well which possibility will have the greatest intellectual and philosophical allure for students, and that's precisely why they are so determined to prevent the comparison.