The terms of demonic obsession, oppression and possession can get really confusing, especially as different denominations mean different things with the same term. For what I have studied, the Catholic terms are defined as follows:
Demonic Oppression- A physical attack upon a person caused by an invisible source. Includes such things as blows, punches, kicks, or scratches by an unseen hand; being pushed down the stairs or thrown against the wall; certain infirmities- such as experienced by the woman in scripture whose back was bent and bowed over (Luke 13: 10-16); various inexplicable health problems. Saints such as St. John Vianney, Padre Pio, St. Margaret Mary, St. Catherine of Siena, etc. have been victims of demonic oppression.
Demonic Obsession- (taken from the book
The Rite) has also been called ‘demonic temptation’ and it involves an intense and persistent attack on the mind of the victim. Generally, these attacks include random and obsessive thoughts that, although often absurd, are so intense that the victim is unable to free him-or-her self. Victims feel tormented by a fixation that completely dominates their thoughts. These thoughts can make the victim think he is going insane, which only compounds the feelings of sadness and desperation. As Italian exorcist Francesco Bamonte notes, ‘Some are thoughts and impulses that urge people to harm others; some make people think that only a pact with Satan can get them out of their troubles or bring them success; some are thoughts to profane the Eucharist; others are thoughts to drive one to suicide.’ Often the obsessions affect a person’s dreams, and terrible nightmares are common" (pg 49).
I also really like Jordan Aumann, O.P.'s explanation- he goes into much more detail than I will here. He says obsession occurs “whenever the devil torments a person from without and in a manner so intense that there can be no doubt about his presence and action…the soul is aware of its own vital activity and government of its faculties, but it is at the same time clearly aware of the external activity of Satan, who tries to excert violence on the individual.”
And specifically about internal obsession, he writes, “The attack on the imagination differs from ordinary temptation only by reason of its violence and duration…sometimes it is fixed ideas…at other times it is images and representations that are so vivid that the subject feels that he or she is dealing with concrete reality (ie, that the devil’s hatred is their hatred, etc).” The area of demonic obsession versus a mental illness such as OCD is very, very murky. Oftentimes, the two go hand in hand, which is why it is so important to have an exorcist assist you, along with a psychologist.
Demonic Possession- The devil takes temporary control of the victim’s body, speaking and acting through the victim, often without the victim’s knowledge. Since a lot of information is available about possession, and because that isn’t the OP’s concern, I won’t go further into it.
Demonic harrassment, whatever it’s form, should be considered a spiritual ‘disorder’, so speak, measured on a spectrum scale rather than a concrete diagnosis. Most victims cannot be precisely diagnosed with one of the three, but fall within the shady areas inbetween them.
If there is one thing I can impart to anyone who is thinking they might be suffering from a demonic disorder, it would be that you should never try to diagnose and cure yourself. Ask a learned priest or an exorcist. Many exorcists are surprisingly approachable and will answer emails or questions if one is brief and respectable.
The best resources I have found for for diabolic activity:
The Rite, by Matt Baglio
Spiritual Theology by Jordan Aumann, O.P.
An Exorcist Tells His Story by Father Gabriel Amorth
The website Padre Pio Center for Deliverance Counseling- Q and A section of spiritual warfare-
saint-mike.org/qa/sw/default.asp
as well the forum for the prayers for spiritual attacks and temptations-
saint-mike.org/warfare/library/?p=22.
Various Catholic articles on the subject:
thecatholicspirit.com/featured/exorcism-it%E2%80%99s-on-the-big-screen-but-is-it-still-in-the-church/
freerepublic.com/focus/f-religion/2661793/posts
catholicexchange.com/2011/02/04/147401/
Sorry for so much info! I would just rather people take a short cut than go the long way like I had to!
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