Exorcism

Exorcism is a method to exorcize demons, commonly through Latin incantations.

Pad of Definitions
As the Pad of Definitions (1.04 Phantom Traveler) says, "exorcism is the act of driving out or warding off demons from persons, places or things that are possessed or infested by the, or are liable to become victims or instruments of their malice. During the exorcism ritual, a solemn and authoritative adjuration of the demon is applied in the name of God or any of the higher powers to which the demon is subject."

Usage
In the series, exorcism are presented as having two parts. The first expels the demon from the occupied vessel (as black smoke) and the second sends the demon back to Hell (shown as the black smoke being sent downward leaving charred marks on the floor). The second part is not mandatory, or can be interrupted allowing the demon to escape and possess another vessel.

It is clear from what Sam Winchester says in Phantom Traveler and Devil's Trap that the boys skip the Invocatio and Psalms and jump directly to the Exorcism proper. It is understandable, given that it is not as though they have all the time in the world, especially in Phantom Traveler.

It is probably the method with the most survival rate for possessed humans, even if some do not make it after the possession is lifted.

Story
Several adaptions are used in the series, all of them being taken from the Rituale Romanum. The following is a direct line-by-line translation of the Psalms for rites of exorcism and Rituale Romanum, with anotations on differents observed in various episodes.

In Phantom Traveler
As seen in Phantom Traveler, a version of the Psalm 68(67) is recited by Sam Winchester as he read it in his father's journal: "Regna terrae, cantate Deo, psallite Domino (...) per caelum, caelum antiquos, (...), glori Patri", which can be translated to English as :"Kingdoms of Earth, sing to God, praises to the Lord (...)". However, a lot of differences between the Psalm are presented. Other...

"Exorcizamus te, omnis immundus spiritus, omnis satanica potestas, omnis incursio infernalis adversarii, omnis legio, omnis congregatio et secta diabolica... Ergo, draco maledicte et omnis legio diabolica, adjuramus te ... cessa decipere humanas creaturas, eisque æternæ perditionìs venenum propinare... Vade, satana, inventor et magister omnis fallaciæ, hostis humanæ salutis... Humiliare sub potenti manu Dei; contremisce et effuge, invocato a nobis sancto et terribili nomine... quem inferi tremunt... Ab insidiis diaboli, libera nos, Domine. Ut Ecclesiam tuam secura tibi facias libertate servire, te rogamus, audi nos."

Translation: "We drive you from us, whoever you may be, unclean spirits, all satanic powers, all infernal invaders, all wicked legions, assemblies and sects... ... Thus, cursed dragon, and you, diabolical legions, we adjure you... stop deceiving human creatures and pouring out to them the poison of eternal damnation... Be gone, Satan, inventor and master of all deceit, enemy of man's salvation... Stoop beneath the all-powerful Hand of God; tremble and flee when we invoke the Holy and terrible Name... which causes hell to tremble... From the snares of the devil, Deliver us, O Lord. That Thy Church may serve Thee in peace and liberty, We beseech Thee to hear us."

Origin
Exorcism (from Late Latin exorcismus, from Greek ἐξορκισμός, exorkismos - binding by oath) is the religious practice of evicting demons or other spiritual entities from a person or place which they are believed to have possessed. Depending on the spiritual beliefs of the exorcist, this may be done by causing the entity to swear an oath, performing an elaborate ritual, or simply by commanding it to depart in the name of a higher power. The practice is quite ancient and part of the belief system of many cultures and religions.

Trivia

 * It appears that the Supernatural production team/writes did a cut and paste from bits and pieces of at least one version of the ritual and possibly some other prayer(s).


 * When Sam first performs an exorcism in Phantom Traveler, he reads a Rituale Romanum from John's Journal. However, over time both Sam and Dean memorize the ritual.