For 36 years Amantini was the exorcist of the Diocese of Rome, stationed at the Pontifical Sanctuary of the Holy Stairs.
He also taught Sacred Scripture and Moral Theology and wrote a book entitled Il Mistero di Maria, about the Virgin Mary.
At the age of 15, on October 9, 1929, he entered the novitiate of the Passionists at the Retreat of St Joseph on Mount Argentario.
Also in 1936, he was transferred to the Sanctuary of the Holy Staircase in Rome, to study for his licentiate in theology at the Pontifical University of St. Thomas Aquinas, Angelicum.
[2] After a long illness, Amantini died at the night on the feast of Saint Candido, his patron.