Antipope JPII taught that all people are saved now (ie not just in a future apocostasis) regardless of faith in Christ; albeit through the Incarnation; the grace of which is mediated through other religions. He is a heretic. VatI said that the pope is infallible "when" speaking ex cathedra; and at no other time. So he can become a heretic otherwise. This is the position of all Roman Catholic theologians prior to VatI; and the opinion of most afterwards. All theologians have said that a heretic cannot be pope, because one cannot be the head of that which he is not also a member of, so when he becomes a heretic he looses his office as pope.
St Robert Bellarmine, De Romano Pontifice II 30:
"A pope who is a manifest heretic automatically (per se) ceases to be pope and head, just as he ceases automatically to be a Christian and a member of the Church. Wherefore, he can be judged and punished by the Church. This is the teaching of all the ancient Fathers who teach that manifest heretics immediately lose all jurisdiction."
St Antoninus: "In the case in which the pope would become a heretic, he would find himself, by that fact alone and without any other sentence, separated from the Church. ÃƒÆ’Ã¢â‚¬Å¡Ãƒâ€š A head separated from a body cannot, as long as it remains separated, be head of the same body from which it was cut off. ÃƒÆ’Ã¢â‚¬Å¡Ãƒâ€š A pope who would be separated from the Church by heresy, therefore, would by that very fact itself cease to be head of the Church. ÃƒÆ’Ã¢â‚¬Å¡Ãƒâ€š He could not be a heretic and remain pope, because, since he is outside of the Church, he cannot possess the keys of the Church." (Summa Theologica, cited in Actes de Vatican I. V. Frond pub.)
St Alphonsus, Bishop and Doctor of the Church: “If ever a Pope, as a private person, should fall into heresy, he would at once fall from the Pontificate.” (Oeuvres ComplÃƒÆ’Ã†â€™Ãƒâ€šÃ‚Â¨tes. 9:232)
St Francis De Sales, The Catholic Controversy, p 305-306 : "Now when he [the Pope] is explicitly a heretic, he falls ipso facto from his dignity and out of the Church..."
The one exception to the princple prima sedes a nemine iudicatur (the first see cannot be judged by anyone) is nisi devius a fide deprehendatur (except when he is convicted of deviation from the faith). It is the obligation of the faithful to depose the pope when he falls into heresy. He is stripped of all rights. Granted some theologians, including Garrigou-Lagrange, have postulated that a false pope can still act as administrator, and if he is functioning as such, it might be beneficial to follow his direction in issues not pertaining to faith. But he is still not pope.
Please see the post in "Faith Issues" about JPII's involvement at Assisi.
LOL, good thing I am not a Traditional Roman Catholic, because then I would have to go to a legalistic and papistic Sedevacant or SSPX church. I believe that the Catholic and Orthodox churches constitute the One True Church; though the fullness of faith is found in the Orthodox church. This means that I do not have to believe the VatI dogma. Praise be to Jesus Christ! Your Church is Immaculate, even if the Roman pope is a heretic, for the Episcopate remains. Glory to God in the Highest!