Father Gabriele Amorth, the founder the International Association of Exorcists who served as exorcist for the diocese of Rome for 30 years, died Friday at the age of 91.

Arguably the best known Catholic exorcist in the world, Father Amorth had been hospitalized for several weeks at the Saint Lucy Foundation Hospital in Rome due to complications from pneumonia.

Father Amorth was known for his blunt words about the devil and his works, always insisting that Satan’s greatest triumph is getting people to believe he doesn’t exist.

He also earned worldwide attention last year by attributing the work of the Islamic State terror group to the influence of the devil.

“ISIS is Satan,” he said in an April 2015 Facebook post. “Things first happen in the spiritual realms, then they are made concrete on this earth.”

“Biblically speaking we are in the last days and the beast is working furiously,” he said.

A prolific writer, Amorth published numerous books during his career, including An Exorcist Tells His Story, Memoirs of an Exorcist: My Life Fighting Satan, An Exorcist: More Stories, and An Exorcist Explains the Demonic: The Antics of Satan and His Army of Fallen Angels.

During his life Father Amorth performed some 70,000 exorcisms, often sacrificing sleep and leisure time to combat the “father of lies.” Humanly unexplainable phenomena would accompany cases of demonic possession, Amorth said, including the ability to speak languages that hadn’t been studied, superhuman strength, and levitation above the ground.

“Now he rests from his many battles with the devil,” Spanish theologian Father Jose Antonio Fortea told Catholic News Agency Friday.

Born in Modena on May 1, 1925, Gabriele Amorth joined the Society of St. Paul in Alba in 1947, and was ordained a priest in Rome in 1951. In 1985, he was appointed exorcist of the Diocese of Rome by Cardinal Ugo Poletti.

Father Amorth believed that Satanism was on the rise all over the world, and counseled the faithful to resist Lucifer with prayer and vigilance.

In 2001, journalist Stefano Maria Paci asked Father Amorth about the influence of Satan in the Catholic Church and in the Vatican.

“The smoke of Satan enters everywhere,” he replied. “I have no doubt that the devil tempts especially the leaders of the Church, as he tempts all leaders.”

“But thankfully there is the Holy Spirit who governs the Church: ‘The gates of hell shall not prevail.’ Despite the defections. And despite the betrayals,” he said.

“Of course, the devil can win some battles, even important ones,” Amorth observed. “But he can never win the war.”

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