As you've come to realize, "The God Delusion" is not a work of philosophy; it is an irrational, emotional outburst, a polemic of pure bigotry. That's why the screed is popular--bigots read it to confirm their bigotry. Such is atheism.

Immanuel Kant, over 200 years ago, demonstrated that there are no rational arguments for or against the existence of a supreme being. Only fools still try. But, fundamentalists of all stripes keep trying, with Dawkins being a one of the fools.