In the study of religions, “possession” means being dominated by extraordinary forces of good, personal or non-personal (see Enthusiasm). In Christian usage, it means the exceptional action of non-human but personal evil, the “principalities and powers”. Someone is “beset” from outside or taken possession of from within. He can fall sick, physically and mentally, and break out in aggressive and blasphemous rages, but though his responsibility is diminished or at times totally absent, his personality is not fully disintegrated.

The many evil powers mentioned in the NT appea…