We take a lot for granted, we humans. Gravity keeps us comfortably in our seats. Light comes in the morning, only to wane in the night, fading into pale starlight. The Earth spins on its axis in the darkness of space, making its way around the sun in a solar system that sits on a safe and quiet arm of the Milky Way galaxy. We know how all these things work. We do not fret, because we can comfortably explain, quantify, and catalog every phenomenon to ourselves, and those natural systems we have yet to understand will no doubt soon submit to the searching power of the mind of man.

But my interview with Vatican-trained exorcist, Father Gary Thomas, tells a very different story.

In religious lore all over the globe, there is depicted a world that exists in the peripheral, beyond the natural laws that bind our material forms. A world of spirit rather than flesh.

In the Christian tradition, God rules over all creation, material and spirit alike. He commands hosts of angels, and examples of interaction between these heavenly beings and mankind are littered throughout the Bible. Angels do the bidding of God, and are sent out as messengers, healers, rescuers, and sometimes destroyers that have wiped entire cities from ancient maps and decimated armies. All, though, serve the will of God, and the will of God is always good, brought forth from a place of unimaginable love for all creation. These angels are beings of goodness.

But not everything in the spiritual realm is holy. There is darkness, as well—darkness that once was light.

Revelation 12:7-9 reads, “Then war broke out in heaven. Michael and his angels fought against the dragon, and the dragon and his angels fought back. But he was not strong enough, and they lost their place in heaven. The great dragon was hurled down—that ancient serpent called the devil, or Satan, who leads the whole world astray. He was hurled to the earth, and his angels with him.”

Those angelic betrayers are now among us—spiritual beings so corrupt that they saw the very face of God, and yet still chose to betray Him, likely because of an intense jealousy of mankind. God, after all, made us in His image, and loves us dearly. And these angels who betrayed the God of the universe because of their jealousy of man were cast down to earth—with us.

What could be more terrifying? We are faced with a celestial foe that harbors no end of ill will toward mankind, an enemy that we cannot see or hear or touch, but who can affect us nonetheless. What can we possibly do in the face of this?

It is this question I took to Fr. Gary Thomas, mandated exorcist for the Diocese of San Jose, California. In 2005, Fr. Thomas was sent to study at the Vatican’s Athenaeum Pontificium Regina Apostolorum in Rome, where he completed 40 hours of study in the sacred rites of driving out demonic presence—he became an exorcist.

With only about 14 Vatican-certified exorcists working in the U.S. as of 2011, Fr. Thomas’s knowledge is a rarity—so rare and interesting, in fact, that journalist Matt Baglio chronicled Fr. Gary’s learning and experiences into the book, “The Rite: The Making of a Modern Exorcist,” which served as the inspiration for the subsequent film. Father Thomas spent about a week on the set of the film, as well, advising director Mikael Hafstrom and actor Anthony Hopkins, drawing on his experiences with real cases of possession.

In our phone interview, I found Fr. Thomas to be an exceedingly intelligent, fair-minded man whose passion for his calling was half-hidden in a quiet thoughtfulness. Over the next thirty minutes, he proceeded to answer each one of my questions, his responses to which are here, provided for the benefit of those who wish to know how to protect themselves from demonic activity.

"The oldest and strongest emotion of mankind is fear. And the oldest and strongest kind of fear is fear of the unknown."

-H.P. Lovecraft

“What is a demon?”

A demon, according to Fr. Thomas, is “an angelic creature who rebelled against the sovereignty of God, and who aligned itself with Lucifer. Demons are fallen angels, and retain their angelic nature even though they’re fallen. They’re aligned with Satan—that’s implied. Scripture, the book of Revelations, tells of a third of the angels rebelling against God. What does that mean numerically? We don’t know.

We just know that there was this rebellion in heaven and that Lucifer and some of his company were expelled. But they are angels who have fallen out of grace with God, and rebelled against God over envy and jealousy related to humanity.”

The stance of the Catholic Church is that demons are fallen angels, and retain their angelic nature. They’re not human ghosts or Nephilim spirits or benign passersby on the cosmic scale. They’re powerful, malevolent entities.

This fact of their power brought me to my next question.