Among contemporaries he passed for one of the most formidable polemical or gladiatorial rhetoricians; and a considerable section of his extant works are invectives.
It is the chief of the dogmatic or polemical works, and rules the accuser out of court at the very opening of the case.
He also displays in this work a considerable knowledge of the Rabbinical writings and a skilful polemical method which was surpassed by none of the later anti-Jewish writers.
Of the many prophetic and polemical works that were attributed to Joachim in the 13th and following centuries, only those enumerated in his will can be regarded as absolutely authentic. These are the Concordia novi et veteris Testamenti (first printed at Venice in 1519), the Expositio in Apocalypsin (Venice, 1527), the Psalterium decem chordarum (Venice, 1527), together with some "libelli" against the Jews or the adversaries of the Christian faith.
The fragment of a polemical treatise against the Neoplatonist Proclus is now assigned to Nicolaus, archbishop of Methone in Peloponnesus (fl.