[NTHockey]

Short answer is that the pope, any pope, cannot be a heretic. He can be an apostate, meaning he has gone against the church. Francis is an apostate.

[ebb tide]

Short answer is that the pope, any pope, cannot be a heretic.

Sure they can.

[Campion]

An apostate is one who has rejected the Faith altogether; i.e., he says he's not a Catholic anymore.

A heretic is one who obstinately rejects one or more revealed truths of the Faith.

Can you explain why a Pope cannot become a heretic? (Not, you understand, why a heretic cannot remain Pope. That's different.)