If Satan can influence our conscious thoughts and inner desires, as he must if we believe that he can tempt us, then I believe that he (and God) can also affect our mental health. Again, to science, this is absurd simply because science, in and of itself, does not recognize Satan or God as being real. How the soul, mind, spirit, and brain interact is more of a philosophical question which I personally believe is well beyond human understanding, but clearly, there is a difference between the mind and brain.
I am totally with you in relation to the fact that we cannot ignore that some issues with the human mind may be directly related to the influence of evil spirits, surely this is what the majority of Saints in the centuries gone passed would have understood of schizophrenia or other such mental disoders. (Am I wrong on this?).
However, the other thing we cannot ignore, is that material substances, say for example a mushroom that contains hallucinogenic compounds, can and will make one hear and see things that are not there (or are they, that’s a different question). The physical chemicals in the mushroom, interact with the chemicals in our brain, and the result is that we hear and see things that we would not normally.
My point being is that, while we can definitely say that spiritual beings can influence or disturb the mind of a person, we can’t ignore (what I think most previous posters are attempting to point out) that sometimes the cause of a disturbed mind may have it’s origin in something wholly material - like the ecstasy pill being the trigger for the schizophrenia of a previous posters friend.
I absolutely agree that God could cure peoples mental issues, just as he could make the paralytic walk - but He does not always do this, why? That’s the tough question down the ages.
Do we say that the paralytic is the way they are because of demons?
If not, why should we say the same for schizophrenic people?
Just as the neurons are not functioning in a person who can’t walk, the neurons may not be functioning correctly in a schizophrenic person.
However my question with all this also is, isn’t the root cause of disease spiritual, as in sin?
Someone said here that sin causing disease was an Old Testament construct, what did they mean by that?