Another reason some people today consider Pope Francis invalid is because of heresy. The topic of a heretical Pope, even though Saint Robert Bellarmine said this is an opinion, was not presented as the final or definitive teaching of the Magisterium. The magisterium, meaning the teaching authority of the popes and the Ecumenical Councils, never promoted or accepted this theological opinion of the automatic loss of the papacy by a heretical Pope. There is only one case: Pope Paul IV in the 16th century issued a document, a bull, which declared that a heretic cannot be pope.
