I am struck by a few things.
First, in the blog post he mentions:
It assumes that all things we call religion or religious impulses are essentially the same or have some common core. This faces the philosophical problem of properties and propositions in general. For example, take the property of redness. Is there something that all objects we call red have in common? And if there is, is this the same kind of thing we call religious belief?
In fact there is something common to all things red: the wavelengths of light that are absorbed. I think what he is asking is whether we experience red in the same way as our friend. In fact, it is quite likely, and it is not a philosophical idea at all. It seems to me more and more that philosophy tries to handle questions that are out of reach for science (for the moment) but the solutions found in philosophy evaporate or are insubstantial once we really understand what is going on. Tom Mitchell has done some very interesting work with looking at fMRI data in his "Brains, Meaning, and Corpus Statistics" talk (talk slides on his home page).
In the work, he compares fMRI data from different individuals, and finds that he can correctly identify images and words from brain activity of one person, using the associations between the images and words derived from the brain activity of other people. This strongly suggests that the internal representations of words and concepts may be very similar between individuals. Not only that, but that we have the possibility of determining what those are and not just leave it up to philosophical ruminations.
Dawkins mentions belief in authorities as a psychological tendency that may lead to religious thinking under the right circumstances. I would further add the brain's tendency for seeing patterns where there are none as the other piece of the religious-thinking puzzle. It is evolutionary advantageous to see tigers where there are none as opposed to not seeing tigers where there are some. Not all errors are equally costly. Religious interpretation of experience seems to me to easily follow from these sorts of errors.