Fr. Vincent Lampert — a Catholic priest and the designated exorcist for the Archdiocese of Indianapolis — has witnessed people "foaming at the mouth, growling and snarling" during one of many exorcisms throughout his career. 

Exorcism is an ancient rite in the Catholic Church, that is, "at its core," Fr. Lampert said, "a prayer directed to God or directed against demons." 

That prayer has the power of "commanding" a demon to depart the body of a human "based on the power and the authority of Christ," Fr. Lampert explained. 

"An exorcism really is a command to the demon to reveal itself. And then once the demon reveals itself, the battle against it will begin," he said. 

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That battle can take many forms. Fr. Lampert said that he has "seen everything from levitation of the body," to someone "drop to the ground and begin to slither like a snake across the floor."

Others have their eyes "roll" to the back of their heads. At the site of an exorcism, Fr. Lampert said that there can also be a drop in temperature in the room, "horrible stenches" and an "odor."

It is an unusual experience, even for a priest. 

When Fr. Lampert was first appointed as an exorcist in 2005, he became "one of only 12 stably appointed exorcists in the United States." For his training in Rome, he sat in on "40 exorcisms" in just three months.

He has also served as a priest for almost 32 years since 1991, first becoming appointed as an exorcist in 2005.

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But Fr. Lampert's work has only become busier over the years. He told Fox News Digital that there are thousands that reach out to him every year for his help. "I currently receive about 3,500 requests a year from people all over the world who are seeking help from the church," Fr. Lampert said. 

He described the signs that a person has been possessed by a demon. Some speak with "a very deep and authoritative voice," he said, and their "complexion" can also change, becoming darker. He also said that he has also seen the eyes of a person possessed "turn green" and their "pupils become like a serpent." 

As Fr. Lampert put it, these are all signals of a demon trying to say, ‘Don't mess with me because I'm more powerful than you.’"

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Fr. Lampert also explained why exorcisms are not filmed and released by the Catholic Church. 

"That’s to protect the identity of the person who is possessed," he said.

Fr. Lampert acknowledged that some critics argue that filming the exorcisms would provide the best "proof" for its validity. But he took issue with the premise that all would believe if confronted with video evidence of a live exorcism. 

"I think we all know that we live in an age where technology can be manipulated. So even if one were to claim that they had a video of an exorcism, it doesn't mean that all doubt will go away," he said. 

As to the fascination with demons and Satan, Fr. Lampert said that "the devil is a big business today."

"There is still this fascination with the devil and the world of the demonic," he added, commenting on the movie "The Pope’s Exorcist" that was released earlier this month.

Fr. Lampert said that while he has not watched the film, he is a member of the International Association of Exorcists (AIE) which is a "group of 750 priests and their helpers from throughout the world." It is the same organization that was founded by the movie’s protagonist, Fr. Gabriele Amorth. "The AIE has not given good reviews to the movie," Fr. Lampert said. 

"They don't believe that Fr. Amorth is portrayed correctly, and they believe that the focus really is on the devil and not on Fr. Amorth and what he tried to do during his ministry of helping people who were possessed," he explained.

Fr. Lampert was emphatic that demons were real forces in the world, telling the story of a young girl whom he said was possessed by a demon after she was abused. 

"I did an exorcism on a person who was raped by her father, beginning at the age of seven and then felt broken and battered from that."

"At the age of 12," he said, the girl's father "turned his attention to her younger sister. So she's broken. She's shattered. She blamed God for allowing this to happen," Fr. Lampert said.

That led to the girl choosing to leave the church for "more than 38 years," Fr. Lampert said, until a friend encouraged her to return, an opportunity that allowed her to meet Fr. Lampert in person. She then asked him to help her, as she believed she was being inhabited by a demon. 

Fr. Lampert said that when he said the name of "Jesus" in her presence, the woman’s "eyeballs turned green and her pupils became slanted like a serpent. And the voice came out of her mouth and said, 'Who's he? He has no power over us.'" 

One week later, Fr. Lampert performed the exorcism in a chapel. Fellow priests, the woman in question and her friend were all present, he said. After he blessed the woman with holy water, Fr. Lampert said, her "eyeballs turned green again. The pupils [became] slanted." 

It was then that the demon spoke directly to Fr. Lampert: ‘You can't get rid of us. We've been here too long, and you're not strong enough.’"

During the rite of exorcism, Fr. Lampert breathed on the face of the woman, recalling a moment in the Gospels when Jesus breathed on the face of his disciples. 

"The person came flying out of the chair and landed on the floor. I and the other priests picked her up and she's glorifying and praising God. And there was a glow about her," Fr. Lampert said, that was almost like a halo. 

"They're not radiating their glory. They're radiating the glory of God. It's a sign that a person really has taken their free will and united their free will with the will of God. That's a sign that I always look forward to knowing that a person truly has been liberated from demonic possession," he said. 

That session took 45 minutes.

Fr. Lampert left off with one thing that he said everyone should understand about exorcism. "Ultimately," he said, the main actor in the rite of exorcism is not the priest — it’s God. 

"Even in an exorcism, Jesus is not a bystander. He's the main actor. So it's not what I'm doing as an individual, it's what Christ wants to do in the life of a person. Anytime we turn to Christ he is always going to accept and welcome us with open arms. And in doing so, we can defeat anything the devil is trying to do to us," Fr. Lampert said.