What philosophical evidence is there against believing in non-physical entities?

[Panatheist]

Well I have to say that I am not philosophically well versed. I would like to change that, but I can give you ideas for food for thought, and perhaps others more philosophically inclined may be able to build on that if they wish depending how the conversation goes.

I have my entire life had experiences of beings and other phenomena that are seemingly not physical. Everyone experiences something like this to a degree I think -- thoughts, mental visuals, dreams.

I do not believe my internal visual and audial experiences are mere fancy either -- it's pretty annoying to hear that from people who have no information of how I experience such phenomena. Some of these experiences have been very complex and have facilitated the rapid processing and healing of psychological trauma -- in fact, I have every reason to believe those experiences are largely a mechanism for addressing and repairing that trauma. Thus I tend to interpret these experiences, many of them very moving, in psychological terms.

There are a number of ways altered states may be induced. Though my experiences are not drug induced, that is certainly one way to do it -- by manipulating chemicals in the brain. There is a correlation between those physical changes and mental experience. Certain forms of meditation and prayer in more subtle ways also affect changes in the brain and thus lead to altered states including but not limited to visual and audial experiences not directly related to the surrounding physical environment. Sometimes the experiences may be spontaneous, but I would think there would be a physical correlate. Near-death like experiences (involving a tunnel, a light, spirit beings, etc.) can be produced by drugs, hypnosis, fear of immediate injury or death. Aspects of NDEs are reported in patients when certain parts of the brain are stimulated (the life review).

Though these correlations cannot disprove a spiritual dimension they incline me to believe that all such experiences are produced by the brain. All of the evidence suggests that we cannot experience anything without a brain or nervous system, and due to injury or unconsciousness we may not experience anything even if the brain is alive.

If communication with spirits or experience of non-material realms are occurring I want to know how the interaction is occurring. What does it even mean to be a non-material being? Such a term suggests what an entity or realm is not, not what it actually is. How can a non-material being exert any influence over the physical world at all? How could such beings manipulate the brain to produce experiences or communication if they do not consist of physical energy with which to interact with the material realm?

After a lifetime of apparently unusual experiences, some of them involving striking intuition, I still have no reason to assume that any of it involved a non-material being or realm or passed on any insights or information that could not have been arrived at based on what I already knew or had good reason to suspect even if I was not always conscious of all the factors involved. At most some of the experiences involved intuition which we all have in one form or another, but definitely not extra-sensory perception or psychic abilities.

I value my experiences for what they are and for the benefits they have given me, and I strongly dislike when such perceptions are dismissed by people who likely have no personal experience of anything of the kind. Still, I have not needed any supernatural hypothesis to account for them. It is not apparent to me how such explanations actually explain anything at all.