Evil spirits are normally viewed as "influences", and their effectiveness in the lives of people is undetected because they are not seen as real personalities that are totally and unreservedly evil. People discuss the issue of whether or not a Christian can be "possessed" by an evil or unclean spirit; all the while, these ambassadors of Satan are busy doing the thing they do best - deceiving men and women, both unsaved and believer alike.

They are unrelentingly evil in all their desire and action.

They enjoy "vexing" humanity.

They are classified as "wicked" with ascending degrees of wickedness.

They have the ability to inhabit the human body as well as the bodies of animals to do evil.

They are sometimes connected with "infirmities."