spiritual experiences of that sort are extremely rare

I don't know about that. I have a feeling that these spiritual experiences cluster and that in certain times and social contexts they are pretty common, and in other times and contexts -- not so much.

I think this indicates that there is a full spectrum of these experiences -- from mild unease at something being vaguely there to being fully and completely overwhelmed by God's presence. The extremes follow their own paths (one to being ignored and the other to becoming a full-fledged mystic), but the middle depends a lot of social expectations, priming, feedback loops, etc. The same experience could be described as presence of God and as "that was weird, my mind must be getting loopy".