To be oppressed by demons refers to when people are completely possessed and controlled by demons, even against their will, and in defiance of their desire to be free of these demons. They are not sinning, but suffering, also from the falls, cramps, and foolish words and actions brought upon by Satan’s command (see Matthew 17:14–15); however, this is not the same as what we know of as insanity.
Oppression by demons refers to when people are under the complete possession of evil demons sent by Satan and which exercise complete control over their souls and bodies. These people are controlled by demons even against their will. They do not cooperate with a demon as Judas did, but they experienced the demon’s control as a form of oppression from which they desire to be liberated. They therefore do not sin, but are suffering. Externally this state of being possessed manifests in falls, cramps, pains, foolish actions and words spoken at the command of Satan (see Matthew 17:14–15). Demon possession must, however, not be confused with what we know as insanity.1
24 Sa renommée se répandit dans toute la Syrie, et on lui amenait tous ceux qui souffraient de maladies et de douleurs de divers genres, des démoniaques, des lunatiques, des paralytiques; et il les guérissait.