Most people do not discern between the mind, soul and heart, let alone even amongst believers, able discern the soul from the spirit or soulish things from spiritual things.
A believer who falls out of fellowship, be a known or unknown sin, is capable of committing the most heinous sins imaginable or even be the most antichristian person conceivable, although the mind and heart, if begun to be sanctified, are able to place a check on the soul by conscious recognition of sin by the law and our memory and ability to recollect proper behavior and thinking. Such sinful thinking and behavior might and is likely the result of human failing, rather than any other. Besides, why should the fallen angels interfere when believing humans who fall out of fellowship cause so much more bad testimony without their involvement?
The believer who continues to remain out of fellowship, by refusing to return to God by faith in Christ, and by refusing to confess known and unknown sins to God through faith in the Cross, simply remains unforgiven for those post-believing sins, and is not being further sanctified, but might very well continue to degenerate in his/her spiritual condition, as well as degenerate in his/her mind and heart until they return to God and confess their sins to Him.
Most believers, even those who attend church regularly, or study theology, when out of fellowship, scar their souls by studying any number of things soulishly, but not through faith in Christ for the spiritual work in the new man by God the Holy Spirit.
Conversely, there may be many a possessed unbeliever, who appears very benign and rational. Just as there are many animals in the zoo, there are many different angels. We might realize how dangerous lions are, but cute and cuddly cougars might appear benign until a very real time of wild behavior. There are elect and fallen angels. Possession of the human soul, the mind or the heart, is known to occur and some of the more obvious situations in Scripture report of quite wild persons manifest from such possessions.
The simple discernment of possession of a human’s soul by another person occurs when the thinking of the possessed person doesn’t originate from the possessed person’s soul, but from the spirit of another.
I agree with most of what you are saying, but your last bit is much easier said than done:
“The simple discernment of possession of a human’s soul by another person occurs when the thinking of the possessed person doesn’t originate from the possessed person’s soul, but from the spirit of another.”
You can’t ‘see’ souls, so discerning where the thinking is coming from is, in my opinion, difficult.
What I think I’m seeing more often now is the substitution of thought with feeling. This intern did a bang up job with me in showing that there was ZERO Biblical basis for the ELCA’s decision to allow homosexual pastors in committed relationships serve. Didn’t matter, she still believed that the ELCA made the right decision somehow.
“I just feel . . . . “ is always the way it starts.
To me, the salvation of Christ is purely logical. It makes sense, and its what a loving God would do. Even the act is logical, and not emotional, and I mean the act of believing in your heart, professing with your lips, understanding with your mind that your salvation comes from Christ, and Christ alone.
The EMOTIONAL part is when, in the aftermath, you finally fathom the suffering of Christ, and you finally grasp the realization that Christ could have, at any point, decided it wasn’t worth it, and could have returned to Heaven. It was always a possibility, and He even asked God to ‘Take this cup from me.”
It’s then that your heart breaks and you are laid bare as the unworthy filth that you were, and how you were adopted and were made clean through no act or merit of your own. For some this may come after a lifetime.
I know priests, and am witnessing priests that are up to their necks in fellowship, and yet are actually carrying out Satan’s will on Earth. Paul proves your point about the very persecutor of Christ’s church was saved and converted into one of the most important of His Apostles. That is ever God’s style.