He was born to humble parents and his given name is not known; his father was Lorenzo Antonini, of Canepina, near Viterbo, and his mother, Maria del Testa.

[4] Antonini's zeal for the genuine reformation of conditions in the Catholic Church prompted him to present Pope Adrian VI with a Promemoria.

[6] He was universally esteemed as a learned and virtuous member of the great pontifical senate and many deemed him destined to succeed Pope Clement VII.

[4] Antonini knew Marsilio Ficino from a visit to Florence, and he was familiar with Pico della Mirandola's interpretations of the Kabbalah, which he was to surpass in the depth of his understanding; his interest in the Talmud led him into correspondence with Johannes Reuchlin.

When the turmoil of war drove Levita from Padua to Rome, he was welcomed at the palace of the bishop, where, with his family, he lived and was supported for more than ten years.

In the course of Reuchlin's conflict with the obscurantists (1507–1521), in which the preservation of the Jewish books was at issue, the cardinal wrote (1516) to his friend: "While we labour on thy behalf, we defend not thee, but the law; not the Talmud, but the Church."

[8] The British Museum contains a copy of Makiri and the Midrash on the minor Prophets, written for the cardinal at Tivoli, in the year 1514, by Johanan ben Jacob Sarkuse.

When urged by Pope Clement VII to publish his works, he is said, by the Augustinian historian, Friar Tomás de Herrera, O.E.S.A., to have replied that he feared to contradict famous and holy men by his exposition of Scripture.

The Pope replied that human respect should not deter him; it was quite permissible to preach and write what was contrary to the opinions of others, provided one did not depart from the truth and from the common tradition of the Church.

The six books of Antonini's important correspondence (1497–1523) concerning the affairs of his Order, much of which is addressed to Friar Gabriel of Venice, his successor as Prior General, are preserved in Rome in the Biblioteca Angelica.

Cardinal Joseph Hergenröther, a leading Church historian of the 19th century, praised particularly the circular letter in which Antonini made known (27 February 1519), his resignation of the office of Prior General of the Augustinian friars.

[10] Other of Antonini's known works are a commentary on the first book of the Sentences of Peter Lombard, three Eclogae Sacrae, a dictionary of Hebrew roots, a Libellus de ecclesiae incremento, a Liber dialogorum, and an Informatio pro sedis apostolicae auctoritate contra Lutheranam sectam.