Dr. Dawkins' primary problem, his delusion if you will, is his a priori commitment to naturalism. As Dr. Plantinga observes:
The real problem here, obviously, is Dawkins' naturalism, his belief that there is no such person as God or anyone like God. That is because naturalism implies that evolution is unguided. So a broader conclusion is that one can't rationally accept both naturalism and evolution; naturalism, therefore, is in conflict with a premier doctrine of contemporary science. People like Dawkins hold that there is a conflict between science and religion because they think there is a conflict between evolution and theism; the truth of the matter, however, is that the conflict is between science and naturalism, not between science and belief in God.
Perhaps this is why Dr. Dawkins can claim only one convert to his religion. On page 117, his apparent affection for Douglas Adams, deceased author, is admirable and he refers to him as "possibly his only convert." Prayerfully, it will be his last.
The God Delusion is full of bluster and bombast, but it really doesn't give even the slightest reason for thinking belief in God mistaken, let alone a "delusion."
The naturalism that Dawkins embraces, furthermore, in addition to its intrinsic unloveliness and its dispiriting conclusions about human beings and their place in the universe, is in deep self-referential trouble. There is no reason to believe it; and there is excellent reason to reject it.