They were blind to the truth that was staring them in the face. But this a bad reason for rejecting anyone's views, as it tells us nothing about the truth or falsity of what they believe. One can both want to believe something and it can be true. The charge of wishful thinking can equally well be laid against those who believe there is no God. So the most basic claims of religion are scientific.
Religion is a scientific theory.
However, while Dawkins uses the terms 'scientific theory', 'religion' and 'religious theory', he offers no demarcation criteria for scientific or religious theories which would enable us to evaluate his assertions. This is a logical point, unaffected by whether one does or does not believe in God oneself. In collapsing the distinction between these two types of explanations and treating them as alternatives, Dawkins is committing a type-error in explanation. Dawkins has ready access to the whole theological collection of the University of Oxford if he wishes to avail himself of its resources. In case it should appear otherwise from this critique, no personal animosity is intended or felt.