This direct assault covers what the Bible refers to as "demon possession," the outright control of human personality by the power of a wicked spirit. It also extends to such activities as soothsaying, occultism, spiritism (or spiritualism), and related black magic arts such as astrology, fortune telling, …

Demon possession is defined by the a human who has become inhabited or "taken over" by a demon and who cannot, consequently, exercise his own will -  Mark, Chapter 5, ver. 12.

First, the Bible itself is very careful to distinguish between mental illness and demon possession. The writers of the Scriptures were certainly aware of this distinction. One of them, Luke, was a physician himself and was certainly acquainted with the distinctions between diseases and mental illnesses, as well as demon possession. In Matthew 4:24 a careful distinction is made between those who were afflicted by diseases, those who were demon possessed, and those who were lunatic or mentally ill. Luke refers to the same thing in Luke 4:40-41.

It should be noticed that ancients also had a sort of faith in the prophetic words spoken by those whom they believed to be possessed by demons, and this was sometimes a component of ancient oracles. Later, exorcists of the Church have stried to improve its knowledge of demons and theology by asking precise questions to the (demons that occupied) possessed.

Demon possession may last for relatively brief periods of time for any one individual. The rest of the time, the victim of demon possession may appear normal by social standards. Only when a demon is in residence will its presence be detectable in terms of the behavior of the victim.

The behavior of these short-term victims of demon possession is characterized by four basic symptoms. These symptoms may appear alone or in groups, for just seconds of time, and in varying degrees of intensity. The four basic symptoms are: violence, lust, greed, and an unnatural power of persuasion.

Satan, the Prince of Demons, seems to use three different activities or approaches in his attacks by demons. It is only at the last step that the subject has lost all his free-will and is totally under control of the Devil.

In Acts 10:38 we read that Jesus went about "healing all that were oppressed by the devil; for God with with him." The original word means "to exercise dominion against one, to be overpowered." The demons put pressure upon and exercise harsh control over one who is oppressed.

Secondly, we read of people who were "vexed with unclean spirits" and were healed (Lk. 6:18, Acts 5:16). Webster's dictionary defines obsession as "to haunt or be troubled in mind to an abnormal degree; the state of being obsessed with an idea, desire, emotion - one that cannot be got rid of by reasoning."

Thirdly, Scripture speaks of some "possessed of demons" and indwelt by them (LK 8:36; Acts 8:7; 16:16). Possession means to be completely under the control of a demon. Those thus afflicted in the time of the Lord expressed the mind and consciousness of the demon or demons indwelling them.