He received the habit as early as 1480, studied Semitic languages in Rome and was appointed lector at the convent of Ara Coeli; he also held the office of provincial in the province of Bari, and that of penitentiary under Leo X. Galatino wrote his chief work De Arcanis Catholicae Veritatis, at the request of the pope, the emperor, and other dignitaries, in 1516, at which time, owing mainly to John Reuchlin's Augenspiegel, the famous controversy on the authority of the Jewish writings was assuming a very high-profile.
Resolved to combat the Jews on their own ground, he turned the Cabbala against them, and sought to convince them that their own books yielded proof of the truth of the Christian religion, hence their opposition to it should be branded as obstinacy.
He had borrowed largely from the Pugio Fidei of the Dominican Raymond Martini, remodelling, however, the material and supplementing it with copious quotations from the Zohar and the Iggeret ha-sodot of the Jewish convert Pablo de Heredia.
300–308) he vehemently defended himself and his party against the charge of having forged the last-named book, which he firmly held to be the work of Rabbenu ha-Kadosh.
Galatino was aware, no less than his critics, that his De Arcanis had many shortcomings, both in matter and form, and he begged his readers to consider that he was compelled to finish it within the space of a year and a half.
For the rest, Galatino's extensive knowledge and his thorough acquaintance with Greek, Hebrew, and Jewish Aramaic is fully borne out by his numerous other unpublished writings.