Dear Brother Mike, you are very correct in saying that the debate on demonology comes from "terminology" - in many cases, but not all.
Though we can agree that a truly born-again Christian cannot be demon possessed, which also means that they have a demon "in" them - it is equally unBiblical to use the term "cast out" with Christians. Having a demon "in" a person is the only time we would need to "cast out" that demon and in a truly regenerated Christian - those words are not the appropriate terminology. If we type in "cast out" into an e-sword or similar program as a 'phrase' and search the N.T., we'll see how that phrase is used - always with those who have a demon 'in' them. "Deliverance" is another word that one should do a Biblical Search on.
I wrote on another thread how that before I was saved-saved, I was studying psychiatry - and then when I heard the full Gospel, I gave that part of my life to GOD and the one and only "extreme" I got caught up in after full-salvation was 'demonology', due to my own fears of counterfeits because of the supernatural gifts.
To make a very long story as short as possible - within months of The LORD showing me through His Word alone that the demonology that I was being taught, and was believing, was unScriputural, the very next set of books the LORD gave me were Watchman Nee's. All of this happened within my first year in The Church, almost like a crash course.
So, combining my extensive research on demonology, my knowledge of psychiatry and now having Watchman Nee to learn from - I was able to go "Scripture Only" and find that when GOD comes into a life, He cleans house completely and if there's any problems there-after, it's due to the "self-life" and non-Biblical beliefs that stem from 'self'.
The self is just pride, to lesser or greater degrees. All "mental illnesses" as the secularists call them, are from us being "self-focused" in one way or another. Even if we believe a "heresy", which is defined as "the belief chosen" - it is because of "self". To be "self-focused" can be out of even so-called honorable causes - as in a hyper-conscience that fears displeasing GOD and not just the "self-focus" of a selfish person. "Self-consciouness" can be selfish or just from fear of displeasing GOD or men - but in the long run - it's from not knowing Him and His Word well enough.
Nee even teaches that too much "introspection", in a desire to please GOD, is wrong.
You've read a lot of Nee as well, so I believe you are following my thoughts.
"Self" whether it be from pride or fear, will cause what the secularists call "neurosis", "disorders" or "psychosis".
What we're dealing with - all of us - is self - to one degree or another.
We know from Job that GOD can use a devil to work His work at exposing what's really inside of us - that 'self' life.
These "mental illnesses" are the extremes of a self-life and the enemy of our souls will take advantage of anyone in the state of being self-oriented and GOD allows that, at times.
The person is truly in need of dying to self, no matter what their problem is, than the enemy has no grounds to stay. I'm adding here, the enemy has no ground but what The LORD allows to get our minds where they belong.
Adding also the terms - "self-pity", "self-glory", "self-centered", "self-conscious", and so forth.
Many people have been actually 'physically healed' at these heretics meetings because the heart of the person seeking the healing was in fact "looking to GOD" for the healing.
In the same way - some have been delivered from mind-problems through submitting themselves to the prayers of those who may think it's just demons - because the person is finally fed-up with acting irrationally.
Yes, some may be externally-oppressed but the root cause is "self" and GOD will use this external-oppression to make the person tired enough with what they're doing or behaving like or experiencing to finally seek help from fellow Christian's prayers.
There are people who are "self-consumed" and those are the ones who will eventually develop one of the three classifications that the world terms as mental illnesses.
GOD is GOOD and when a person is genuinely saved - GOD cleans house completely. To teach otherwise is to rob Him of His Goodness, Faithfulness and Abilities.
All blame goes to one manifestation of the self-life or another. It's all self. He only uses the enemy to keep self at bay - as He did with the Apostle Paul, even Before Paul became proud, but so that he wouldn't become proud, He sent him a "messenger from Satan".
Not too many people can claim to have been through the remarkable spiritual experiences that Paul went through - and if they say that they have - they're proud already :) - but Paul's exceptional experiences is why GOD gave him that thorn. Paul never sought "deliverance" or for anything to be "cast out". Paul only asked The LORD three times that it would "depart From him". It was an outward, not inward "messenger of Satan to buffet him".
There are no cases in the New Testament where a Christian needed deliverance of a "casting out" type.
It is so essential that we understand the workings of our "self-life".
It can also be compared to Peter walking on water. As soon as he took his eyes off of The LORD, he sunk. That's us.
I've known many who have hated Nee only because they hate the dying to self message.
I've known schizophrenics to come to their right mind once they realized the power of their self-life. That being self-focused can make anyone 'sick' and selfish and mean and right to the extremes of hearing voices. Now that is truly "self-focused" at it's max. Paranoia is the same - "SELF" focus to the hilt.
All sin is self and the bottomline truly is - all self is pride.
GOD will do whatever He can to get the pride out of one's life.
To look to or at oneself instead of to Him is pride.
Even if we think our "intentions are good", because we "want to please Him" - what we're truly doing is not 'Trusting Him' to do what He's promised in His Word to do.
We all need to continually, daily, moment by monent, die to self - until the day that we See Him Face to face. Our 'self' is our greatest enemy and like Nee said, there's nothing to fear except our own 'self-life/flesh' getting in GOD's way. We need to take every thought captive to the obedience of Christ and be renewed in our minds by His Word. His Word needs to replace our own thoughts - and that's the way to Life More Abundant... when we forget about self.
Many fall by focusing on the devil when 'self' has been the culprit all along and GOD may only use outward 'attacks' to get our mind where it belongs - off of ourselves and onto The Word of GOD. Bless The LORD of Glory! Our deliverance was at the cross and upon Salvation. We need 'His' Word alone.