You have just shot your entire thesis in the foot. You've been maintaining all along that there can be a science of the spirit. If these things cannot be detected in the world our sensory organs inhabit, then there can be no study of them. Every last single interaction of a person wit the supernatural has been mediated by the meat of our sensation, perception and cognition. We describe dreams, visions, visitations in sensory terms. I would replace the word "materialism", which describes a philosophy and premise (and so sneaks that persona non grata, meaning, in through a back door) with "the material", which describes a condition, a property of our sensory and cognitive equipment, both organic and artificial.
But you've just laid out in plainest language that what you seek, you cannot get, entirely using premises you've provided.
The remainder of the post is a dizzying sleighride down the contradiction thus created into triple-distilled woo. You really are not listening at all. One cannot selectively keep or discard pretty/inconvenient bits of the edifice. Remember Huxley: there is nothing so tragic as a beautiful theory slain by one inconvenient fact. Any system of "learning" or "knowledge" that seeks to ignore that basic principle fails from wilful abandonment of rigor. cn