Michael Freze

“English-speaking practitioners generally use the four following terms to refer to the influence of evil spirits: Oppression – demonic influence which seems to come from outside a person, causing heaviness, weariness or discouragement. Oppressive spirits may be acquired through exposure to a heavy presence of evil: e.g. by participating in deliverance ministry (defined below), by being in a place where occult activities are taking place, by being placed under a curse, by coming into contact with items of witchcraft. Oppressive spirits may be dispelled by a simple command to leave in the name of Jesus. Obsession – demonic influence which seems to reside inside a person, usually afflicting a certain area of a person’s life in the form of strong habitual temptations. A person may open oneself to such influence by deliberately seeking the presence or power of evil spirits through witchcraft, Satanism, or fortune-telling (ouija, tarot etc.); demonic obsession may also occur through other grave sins which are not explicitly associated with the occult, e.g. sexual activity by consecrated or ordained persons pledged to celibacy. The obsessing spirit usually needs to be identified by name and cast out (i.e. commanded to leave) or bound (i.e. forbidden from exerting any further influence). Possession is very rare, and only occurs when human beings wilfully hand over complete control of their life to Satan, by expressly doing so or by embracing grave sin. Formal exorcism, sanctioned by the diocesan bishop, is always required in such cases.Infestation is used to refer to the influence of evil spirits over objects, animals, houses or places.”
― Michael Freze, The Rite Of Exorcism The Roman Ritual: Rules, Procedures, & Prayers of the Catholic Church...Updated! Deliverance, solemn exorcisms, the authority of the exorcist through the Catholic Church.