A Catholic priest says he knows the Devil is real because he has come face-to-face with the demon himself.

Father Carlos Martins has performed many exorcisms during his 20 years of ministry, cleansing people taunted by voices, blackouts and vanishing wounds.

'Exorcists are often asked whether the demonic behavior depicted in the famous 1973 film, The Exorcist, is accurate,' said Father Martins. 

'Except for one phenomenon — the three hundred sixty–degree head turn by the possessed — everything in the movie depicts what a possessed person might do.'

The horrors of demon possession that he has witnessed over the past two decades included levitation, dramatic changes in facial features and an aversion to God.

Father Martins described an exorcism he performed on a middle-aged woman and when it 'was about to begin, she locked arms with a man whose job it was to restrain her and threw him over her head as if he were a rag doll.'

'The man was over six feet tall and weighed more than three hundred pounds. Doing a complete flip in the air, he landed on the floor ten feet in front of her. 

'The woman then pointed her finger at the nearest light switch on the wall, about twelve feet away.  One of the screws holding the switch's cover plate unscrewed itself and darted into her open right hand through the air. 

'She drove it into her left forearm. Later, in the same session, she struck me in the face with such force that I needed two surgeries to repair the damage I sustained to my skull.'

While Father Martins claims to have performed many exorcisms, scientists have suggested that such individuals are only posed by psychological disorders. 

'Some patients who were considered affected by demons and treated with neuroleptics subsequently experienced remission, suggesting strong support for a biochemical theory,' Dr Amin Muhammad Gadit, professor of psychiatry at Memorial University of Newfoundland, Canada, said.

'There may also be a possible explanatory role related to abnormal functioning of brain-stem structures in the region of the fourth ventricle, whether caused by genetic or environmental factors or a combination thereof.'

Other research has suggested the possession syndrome was a result of psychological factors like severe mental illness, trauma, mass hysteria, or cultural beliefs.

But these suggestions have not stopped Father Martins' from his fight against evil.   

In his new book, 'The Exorcist Files: True Stories About the Reality of Evil and How to Defeat It', Father Martins reveals some of the chilling cases he has personally encountered which show the reality of the Devil and his minions.

'People ask me what it is like to battle the Devil. My opponent is hatred himself,' reads the book.

'When I walk into a room to conduct an exorcism, the contempt and disdain of the ancient serpent, the one who refused to obey God, the one who caused our first parents to fall, the one who delights in every human misfortune and suffering, meets me head-on.'

The childless woman

One of Father Martin's most harrowing encounters came from young couple Cheryl and Mark. All the names in his books have been changed for privacy.

The couple failed to get pregnant, causing Cheryl to become depressed and fill the void with an obsession with baby clothes, diapers, infant toys and a crib.

But things took a turn for the worse when she started collecting dead insects, including crickets, grasshoppers, hornets, moths, and butterflies, and putting them next to the empty crib.

'Someone told me they would help me get pregnant,' Cheryl told Mar.

'When they die, their spirits hang around their bodies looking for a place to form new life. Death releases life energy. I want that energy to make a baby happen inside my womb.'

The cribs then began to be filled with dead squirrels and birds, increasing Mark's worries about his wife who had also paid thousands of dollars to a psychic who told her to use the dead animals' life energy to become pregnant.

Finally, Mark followed Cheryl to a pet store and came home to a scene of unimaginable horror.

Cheryl stood over several dead rats, one still twitching, and when Mark confronted her, she said in an extremely deep, alien voice, 'You keep the f*** away from the rats.'

Mark sought help from his Methodist minister, who said, 'You need to go to the Catholics for help with this. They're the only ones with a handle on this kind of thing.'

Father Martins arrived at their home to speak with Cheryl  who turned and said, 'Why did you bring this bastard priest here!'

'Who are you?', Father Martins asked. 

'You know who the f*** I am', Cheryl replied.

After eight exorcism sessions, she was cleansed.

Father Martins wrote, 'In the end, it took the pain, humiliation, and powerlessness of demonic possession to convince Cheryl to look to God—rather than motherhood—for meaning.'

The possessed firefighter

Jeremy, a firefighter in his late 20s, went to Father Martins' church seeking help for his bizarre behavior, days-long blackouts and unexplained injuries.

When he introduced himself, I found Jeremy to be polite, soft-spoken, and gracious—the epitome of a gentleman,' Father Martins shared in his book.

'By his demeanor, no one could guess anything was wrong with him.'

Due to the first impression, Father Martins had to perform the Catholic Church's Rite of Exorcism to be sure the young man was indeed possessed. 

The Rite of Exorcism involves a variety of prayers, including the Lord's Prayer, Hail Mary, and the Athanasian Creed, with the priest using holy water and a cross.

'The ritual requires moral certainty that an individual is possessed before an exorcist may perform it,' the book reads.

''Moral certainty' is understood as the conclusion any intelligent and rational person would reach given the evidence gathered.'

Father Martins and Jeremey spoke privately for a moment, discussing the firefighter's experiences that occurred before the strangeness set in and that is when the source of the possession was revealed.

Jeremy recalled when he was eight years old and his brother's friend brought an Ouija board to the house and invited him to participate.

He remembered the planchette moving in response to various questions the group posed and that night, Jeremy went to bed and saw a dark figure in his room.

'The figure was so black that, although the lights were off, everything else in the room looked like it was in broad daylight. Besides being intensely black, the only additional detail he recalled was that it had a human body but a cat's head,' Father Martins said.

Jeremey said the figure promised to give him anything he wanted in return for his soul. And as a young boy, he dreamed of becoming a firefighter.

Father Martins handed Jeremey a book with a small drop of Holy Water on the cover and when he grabbed it, he 'shot up out of his chair and arched his upper body backward.'

'Demon, who are you?' I asked. 

'%&$# you, priest!' he responded. 'He is mine. He gave himself to me. You will never have him!'

'Demon, I want to speak to Jeremy,' I said. 

He responded with a slow, mocking laughter. 

'In the name of Jesus, I command you to bring forth Jeremy,' I declared. 

Father Minsters repeatedly told Jeremey he needed to renounce the demon and 'claim Jesus as your Lord.'

Jeremy forced the words out, banishing the demon from his body, Father Martins claimed. 

The haunted music box

One of Father Martins' first encounters with the Devil occurred while he was deployed to Afghanistan to teach the Gospel. 

He encountered the Devil's supernatural powers head-on when he helped a woman whose house had been destroyed by fire - so she had moved into her uncle's house.

'Before long, she began hearing voices calling her from adjacent rooms and scratching noises inside the walls,' Father Martins said.

'Appliances turned on and off by themselves, and objects sitting safely on a table or countertop would suddenly drop to the floor. The phenomena terrified her.'

Although the demonic possessions were fairly new to him, he had a strong sense of being watched by something that did not want him to be there.

'Even the air felt like it was against me. I was being warned: Get out or else!' Then the woman shouted, 'That's the music box,'' said Father Martins.

She had previously mentioned a music box that chimed randomly from her uncle's room - even with the winding key removed.

Father Martins blessed every room with holy water - but discovered something shocking inside the music box.

'I reached down and picked it up without any trouble, and as soon as my hands touched it, it stopped chiming,' he said.

'I opened the lid to look inside it. To our mutual shock, the music box held nothing. There were no parts, no chimes, no wind-up mechanism, and no place for batteries.'

'After I sprinkled the box with holy water, she never experienced diabolical phenomena again and lived peacefully within her uncle’s home.'   

Father Martins noted that he would have been content as a priest, without meeting a single demon, saying: 'Though it is a joy to do this work, I have never enjoyed meeting the Devil and his minions.'