An exorcist with 64 years of experience says the ability to tell the difference between demonic possession and mental illness is one of the most vital parts of the ministry of exorcism.

CNA/EWTN is reporting on an interview with Father Cipriano de Meo published in ACI Stampa in which he explained that a priest has to rely on discernment in prayer – and the effect of prayer on the alleged possessed – to determine if he is dealing with a genuine case of possession.

The exorcist will typically say “(a) prolonged prayer to the point where if the Adversary is present, there's a reaction,” he said. “A possessed person has various general attitudes towards an exorcist, who is seen by the Adversary as an enemy ready to fight him.”

There's also no lack of frightening facial expressions, he said, as well as threatening words or gestures and other things,” he said, “but especially blasphemies against God and Our Lady.”

The Catechism stresses the importance of making the distinction between possession and mental illness in paragraph 1673: “Exorcism is directed at the expulsion of demons or to the liberation from demonic possession through the spiritual authority which Jesus entrusted to his Church. Illness, especially psychological illness, is a very different matter; treating this is the concern of medical science. Therefore, before an exorcism is performed, it is important to ascertain that one is dealing with the presence of the Evil One, and not an illness.”

Not all cases of possession look the same, Fr. de Meo said, which is why exorcists must be properly trained.

“It's up to the priest serving in this ministry to know how to deal with the case, by the will of God, with love and humility,” he said.

“For this reason, with my bishop's authorization, for 13 years, I've led a school for exorcists. I've tried to especially prepare those who are beginning this ministry,” he said.

Even though cases of demonic possession are far less common than mental illness, most people are too unaware and unfamiliar with spiritual realities.

And far too many turn to “the chatter of magicians and Illusionists” for answers, rather than “the weapons the Lord has put at our disposal.”

How do we defend ourselves against demonic attack?

Forget looking for radical signs and wonders, Father said. The best defense against demonic possession is a simple and sacramental life of prayer.

“It's absolutely fundamental to get rid of sin and live in the grace of God,” he said.

We are also warned to stay away from anything that involves the occult.

“Consulting horoscopes, astrology, palm reading, interpretation of omens and lots, the phenomena of clairvoyance, and recourse to mediums all conceal a desire for power over time, history, and, in the last analysis, other human beings, as well as a wish to conciliate hidden powers. They contradict the honor, respect, and loving fear that we owe to God alone.” [CCC 2116]