I think that one of the reasons for the irrational hatred of the ID movement is that in the last 50 years a scientific tide has reversed. The hard sciences (as opposed to Darwinian theory, evolutionary psychology and the like), which for centuries had demystified the world and made the transcendent seem increasingly irrelevant, suddenly started providing solid evidence that a materialistic worldview was untenable. The universe was fine-tuned for life, and living things were fundamentally based on highly sophisticated information and information-processing systems. The fact that those of us in the ID movement are promoting public awareness of this has enraged those with a philosophical commitment to materialism, those who counted on the hard sciences to provide ever-increasing support for their worldview.
What was thought to be their best ally is gradually becoming their worst foe, and this is a tough pill to swallow.