There's a difference between "moving experience" and "spiritual experience" that I think both Adam Frank and Eliezer are too quick to dismiss. Seeing a space shuttle blast off is inspirational, but as Eliezer correctly points out there's nothing private or especially religious about it.

Real religious experiences, the sort where you get one, say "Oh, I just saw God" and spend the rest of your life in a monastery trying in vain to capture that sense of connection again, are much more likely to be some very exotic neurological event. Consider for example the commonly remarked upon similarity of "trips" on entheogenic drugs, which we know are screwing with neurotransmission in some way, to mystical experiences.

This sort of a spiritual experience really is absolutely private and absolutely incommunicable. Those who have felt it describe it as a feeling completely alien to and much more powerful than any other feeling they've ever had - which seems completely plausible to me if it's really some sort of weird realignment of cognitive processes. How are you supposed to share or communicate a high-level reprogramming of your brain to someone else? How is a non-neurologist supposed to describe it in any terms other than what they've "experienced"?

This is a passage on Dhyana (a Sanskrit word transliterated into Japanese as "Zen", indicating an extremely high state of mystical achievement) by a certain famous yogi:

In discussing Dhyana, then, let it be clearly understood that something unexpected is about to be described. We shall consider its nature and estimate its value in a perfectly unbiassed way, without allowing ourselves the usual rhapsodies, or deducing any theory of the universe. One extra fact may destroy some existing theory; that is common enough. But no single fact is sufficient to construct one.

In the course of our concentration we noticed that the contents of the mind at any moment consisted of two things, and no more: the Object, variable, and the Subject, invariable, or apparently so. By success in Dharana the object has been made as invariable as the subject. Now the result of this is that the two become one. This phenomenon usually comes as a tremendous shock. It is indescribable even by the masters of language; and it is therefore not surprising that semi-educated stutterers wallow in oceans of gush.

All the poetic faculties and all the emotional faculties are thrown into a sort of ecstasy by an occurrence which overthrows the mind, and makes the rest of life seem absolutely worthless in comparison.

Good literature is principally a matter of clear observation and good judgment expressed in the simplest way. For this reason none of the great events of history (such as earthquakes and battles) have been well described by eye-witnesses, unless those eye-witnesses were out of danger. But even when one has become accustomed to Dhyana by constant repetition, no words seem adequate.

I doubt Adam Frank has ever had one of these experiences, but some of the people he reads have, and some of the people whom the people he reads read have, and he's taken them and misinterpreted them as equivalent to going to Newgrange and being inspired by it. I went to Newgrange once and thought it was pretty neat. I took hashish once and started seriously questioning the nature of mind and experience.

[note: I am not claiming that normal go-to-church-each-week religion is particularly related to this sort of "religious experience". That both of them are grouped together is more of a historical fact than an ontological one.]