A pope cannot be deposed. As he has the highest spiritual authority in this world, he cannot be stripped of his office or forced to resign. Canon law provides that he may *choose *to resign, but it may never be compelled of him. Those who would attempt to do so would not have the authority to do so, and even were a pope forced into exile and an antipope “elected,” the real pope would remain pope until death.
Although it is theoretically possible that a pope might personally subscribe to a heresy, the Holy Spirit would protect the Church from that pope ever infallibly defining the heresy as orthodox dogma. Such a pope would govern illicitly (i.e., govern in an unlawful manner by his willful adherence to known heresy), but he would still be a valid pope.
Whether or not a particular pope *does *subscribe to heresy is another question, and a Catholic should always give the pope the benefit of the doubt. The pope is more likely to better understand what the Catholic faith does and does not require than your average pew-sitter or amateur cyber-theologian and so any judgment that a pope subscribes to heresy should only be undertaken with great caution and after a full examination of the issue. Even then, it is safer for the ordinary Catholic to presume that the fault in understanding is his own and not the pope’s.
Recommended reading:
White Smoke, Valid Pope by Fr. Brian Harrison, O.S.
