I just started reading The Geometry of Love by Margaret Visser, which is a wide-ranging meditation on the architecture and contents of a particular church in Rome. I was struck by her argument, early in the book, that a church intends to remind the people who enter of their mystical experiences. Two friends (one here) recently talked about wishing they could experience God. Visser writes that everyone has mystical experiences, experiences of an intensity that goes beyond the world and our understanding of it. Is she right? I have no idea.
I know I had mystical experiences before I associated them with God and then when I became a believer I went back and re-understood them as experiences of God. Nowadays I have them mostly in the context of therapy, where I will sometimes reach a desperate place and then feel God's light surrounding me. And sometimes not--I don't count on it. Years ago I once remarked to a therapist that the room had suddenly gotten lighter. And she said that was because I had released some of the tension in my neck muscles and more blood was getting to my brain.