“And it came to pass, when the evil spirit from God was upon Saul, that David took an harp, and played with his hand: so Saul was refreshed, and was well, and the evil spirit departed from him.” (1 Sam. 16:23)
If mankind can be called natural, then those who inhabit the Spiritual realm could best be called supernatural, indicating abilities that we do not possess, for they exist as it were in two planes at least. The evil spirit in this verse can best be described by us as one of the fallen angels, a devil, and he was not as far as we know given any specific powers above that which he already possessed, but instead was given the freedom to exercise his will upon Saul at certain times. The one who had prophesized in the Spirit of the Lord (1 Sam. 10:6) was now a tormented king.
Saul had of course been noticed before by our adversary and his cohorts, but up until this point apparently, as far as we know, they were not allowed to interfere with his life, now one was, one specifically chosen and sent by the Most High. Beyond the thoughts of that meeting one must consider this, how did the evil spirit achieve what he was sent to do, how did he change the attitude, the outlook, the demeanor of Saul, how did he make him angry, frustrated and vengeful?
There are many accounts of devils indwelling, possessing human beings in the Scriptures, they had, or perhaps I should say have the ability to manipulate not only the mind and thoughts of men, but their very physical form, most generally causing pain and suffering. The man of the Gadarenes was not only possessed but had the strength to break cords and chains (Mark 5:4) in fact there was more than one of them inside of a mortal body.
“Then goeth he, and taketh to him seven other spirits more wicked than himself; and they enter in, and dwell there: and the last state of that man is worse than the first.” (Luke 11:26) “And the seventy returned again with joy, saying, Lord, even the devils are subject unto us through thy name.” (Luke 10:17)
These beings have been around long before us, and they are still here, unseen yet no less real, they have not diminished in number or strength, their abilities, their powers have not waned at all, and they are still as they have always been, under the direct and unquestioning control of the Lord God. “And, behold, they cried out, saying, What have we to do with thee, Jesus, thou Son of God? art thou come hither to torment us before the time?” (Matt. 8:29)
King Saul was brought to a point of great anger, so much that he tried to kill David several times, but one must consider, was it Saul or the devil, were his thoughts controlled and manipulated or were suggestions, some not so subtle, placed before him that he succumbed to. People for the most part do not care to contemplate these matters so much today, in fact in most circles it is seen as superstitious nonsense, save in some places where many gods are worshipped, where thoughts of the afterlife are considered in ways that do not correspond to the Word of God.
There are angels who serve the Most High, ministering Spirits of mankind (Heb. 1:14) and there are those who have willingly left their first estate, (Jude 1:6) devils whose intent it is to thwart whenever possible the work of God, or to at least hinder it and besmirch His name whenever possible. Without mankind, I can see no purpose for them, without the abilities they have been granted by the Lord God, they have no power.
The devil who was sent to Saul still lives today, he still roams about doing what he has always done since he fell from heaven, dishonoring God whenever possible. They are not, in the greater sense of the word, our concern, we are told to resist (James 4:7) and to keep our armor on and ready (Eph. 6:10-18) our concern is to glorify God. David’s way of doing battle at that time in his life was to play music to soothe the king’s spirit, ours is to praise God for His protection, and give thanks to the Lord for His prayers for us. “I pray not that thou shouldest take them out of the world, but that thou shouldest keep them from the evil.” (John 17:15)