What Would Happen If the Pope Became a Heretic?

Dogmatic Theology: Christ’s Church by Van Noort (1957) teaches: “All theologians admit that the pope can make a mistake in matters of faith or morals when so speaking: either by proposing a false opinion in a matter not yet defined, or by innocently differing from some doctrine already defined. Theologians disagree, however, over the question of whether the pope can become a formal heretic by stubbornly clinging to at error in a matter already defined. The more probable and respectful opinion, followed by Suarez, Bellarmine and many others, holds that just as God has not till this day ever permitted such a thing to happen, so too He will never permit a pope to become a formal and public heretic. Still, some competent theologians do concede that the pope when not speaking ex cathedra could fall into formal heresy. They add that should such a case of public papal heresy occur, the pope, either by the very deed itself or at least by a subsequent decision of an ecumenical council, would by divine law forfeit his jurisdiction. Obviously a man could not continue to be the head of the Church if he ceased to be even a member of the Church.”