The Jewish traditions of heaven and hell and the doctrine of devils were principally derived from the Zoroastrians during the times when the Jews were under the political and cultural dominance of the Persians. 
There was a time in which the belief that physical sickness and mental derangement could be caused by the dwelling of a so-called unclean spirit in the mind or body of the afflicted person was well-nigh universal. 
When the seventy related how “even the devils were subject” to them, they referred to the wonderful cures they had wrought in the cases of victims of nervous disorders. Nevertheless, there had been a few cases of real spirit possession relieved by these ministers.  Jesus really cast out demons in Capernaum.  Amos, the Kheresa lunatic, was not possessed, he just had a nervous disorder, and no spirits supposedly entered the swine.  James of Safed’s son was afflicted with epilepsy and at the same time was possessed by a real mischievous midwayer.  Norana the Syrian woman believed her daughter was possessed but she only was afflicted by a grievous nervous disorder. 
Long after the day of Pentecost the Apostle John, who was the last to write of Jesus’ doings, avoided all reference to these so-called acts of “casting out devils,” and this he did in view of the fact that such cases of demon possession never occurred after Pentecost. 
In general, when weak and dissolute mortals are supposed to be under the influence of devils and demons, they are merely being dominated by their own inherent and debased tendencies, being led away by their own natural propensities.  Rebel midwayers are now interned, held prisoner. 
See also: UB 138:4.3.