Name one Pope, even among the worst of them who were despicable men who professed or taught heresy!
"Furthermore, the Acts of the Thirteenth Session of the Council state, "And with these we define that there shall be expelled from the holy Church of God and anathematized Honorius who was some time Pope of Old Rome, because of what we found written by him to [Patriarch] Sergius, that in all respects he followed his view and confirmed his impious doctrines." The Sixteenth Session adds: "To Theodore of Pharan, the heretic, anathema! To Sergius, the heretic, anathema! To Cyrus, the heretic, anathema! To Honorius, the heretic, anathema! To Pyrrhus, the heretic, anathema!"
While he never spoke or taught the heresy "ex cathedra", as that would be the gates of hell prevailing, he was a believer in it and his writings and actions permited it to continue.