When he was not preaching, John was writing tracts against
heresy of every kind. This facet of his life is covered in great detail by his early biographers, Nicholas of Fara, Christopher of Varese and Girlamo of Udine. While he was thus evangelizing, he was actively engaged in assisting Bernardine of Siena in the reform of the Franciscan Order, largely in the interest of a more rigorous discipline in the Franciscan communities. Like Bernardine, he strongly emphasized devotion to the
Holy Name of Jesus, and, together with Bernardine, was accused of
heresy on this account. In 1429, these Observant friars were called to Rome to answer charges of heresy, and John was chosen by his companions to speak for them. They were both acquitted by the Commission of
Cardinals appointed to judge the accusations. He was frequently deployed to embassies by Popes
Eugene IV and
Nicholas V: in 1439, he was sent as
legate to
Milan and
Burgundy, to oppose the claims of the
Antipope Felix V; in 1446, he was on a mission to the King of France; in 1451 he went at the request of the emperor as
Apostolic Nuncio to Austria. During the period of his nunciature, John visited all parts of the Empire. As legate, or inquisitor, he persecuted the last
Fraticelli of
Ferrara, the
Jesuati of
Venice, the
Crypto-Jews of
Sicily,
Moldavia and Poland, and, above all, the
Hussites of
Germany,
Hungary, and
Bohemia; his aim in the last case was to make talks impossible between the representatives of Rome and Bohemian "Hussite king"
George of Podiebrad, for every attempt at conciliation seemed to him to be conniving at heresy. ==Actions towards the Jewish community==