My position is NOT, as claimed on some websites, that the Pope can never err in his private teachings. My position is NOT, as claimed on some websites, that the Pope can never err in his non-infallible teachings.
Instead, my position, supported with a few long articles here, is the following:
1. Infallible teachings can never err on faith or morals: Papal Infallibility, Conciliar Infallibility, ordinary universal magisterium.
2. Non-infallible teachings of a Pope or Council can never err GRAVELY on faith or morals. Whether a Council can ever err on faith or morals seems to be an open question. My position is that definitive Conciliar teachings on faith or morals binding on the whole Church and approved by the Pope and the body of Bishops are infallible, whether that definitive teaching is in the form of a formal definition or not.
The above statement in #2 implies that a Pope CAN ERR, to a less than grave extent, on faith or morals, in a non-infallible teaching.
3. Dogmatic facts cannot err.
4. Decisions of discipline, other than dogmatic facts, are non-infallible and so cannot err gravely, when those decisions are of the Pope or a Council.
5. The body of Bishops has the same protections from error and from grave error as the Pope ONLY when they teach as a body with the Roman Pontiff.
6. Individual Bishops, other than the Pope, can go astray in teaching and can fail in faith by apostasy, heresy, idolatry, or schism
7. No Roman Pontiff has ever or can ever fail in faith gravely by apostasy, heresy, idolatry, or schism. This has been the constant teaching of the Church since ancient times, and is the teaching of Constantinople III and Vatican I, and is the teaching of Christ in Luke 22:32, according to the constant interpretation of the Magisterium. No Pope can ever be a heretic (formal heresy).
8. No Roman Pontiff has ever or can ever err gravely in non-infallible teachings on faith or morals, for the charism of never failing faith is also a charism of truth. This means that no Pope can teach material heresy under the Magisterium, not even in a non-infallible teaching, not even inadvertently.
9. The same protections from failing in faith are given to the body of Bishops, only as a body (Lk 22:32c), and only as long as they remain confirmed in faith by the Pope.
10. Can a Roman Pontiff privately “teach” (or rather opine) material heresy by ignorance, that is, inadvertently? My opinion is that he cannot. The reason is that the charism of truth and never failing faith is for the protection of the Church. If a Pope could teach material heresy — an idea contrary to established dogma, not a future dogma — even privately, the harm to the indefectibility of the Church might be grave. We also know of no such private error of material heresy by any Pope in the past, which is a sign that this cannot be.
Note well that this does not include a Pope, like John XXII, opining an error that contradicts a future dogma (the Beatific Vision of all the faithful in Heaven immediately). A law is not a law until it is promulgated. Nothing is a formal dogma until it is taught infallibly by the Magisterium. So John XXII was not guilty of even privately teaching inadvertent mere material heresy, since the dogma had not yet been promulgated. It was taught by John XXII’s successor Benedict XII.
Note that the common opinion is that Pope can privately opine material heresy inadvertently. But this “teaching” is not binding on anyone. All are free to disagree.
Ronald L Conte Jr
the reproach of Christ 
Isn’t John XXII’s error re the Beatific Vision of all the faithful in Heaven immediately a “grave” error? Is it your position that this is not a “teaching” and thus he didn’t teach “grave” error, he only privately opined grave error?
It was not a grave error in a magisterial teaching, as it was private opinion. The freedom from grave error applies to the exercise of the Keys of Peter on doctrine and discipline, in what is non-infallible. Then what is infallible has no error at all. Then I would not categorize John XXII’s error as grave since it was clearly stated as opinion, no one was obligated to assent to it, disagreement was permitted, John stated he was working towards a decision under the Magisterium, and he changed his position to the correct one prior to death. Then his successor defined the correct position as dogma. How does that harm the Church? It does not.
Pope Saint Pius X stated, “All the strength of Satan’s reign is due to the easygoing weakness of Catholics.” Is this a non-infallible teaching? Is it merely an opinion? This statement can cause grave harm to the faithful as it can confuse them as there are many pagans in the World.
It is opinion, and does not cause grave harm. Do not be so quick to claim that anything from the Church can gravely harm the Church.
Could you write an answer to this book?
E-book: https://angeluspress.org/collections/catholic-tradition/products/prometheus-ebook
AudioBook: https://www.youtube.com/watch?v=XvnfD43EMHM&t
Book conference: https://www.youtube.com/watch?v=M8NRbaJ603w&t
The answer is the Church is indefectible. Vatican II was approved by Pope Saint Paul VI AND every Pope since then, AND by the body of Bishops (not only at the time of the Council, but ever since then). The claim of that book, that the Council led and is leading the Church astray and that the successive Popes and body of Bishops are also leading us astray, is contrary to the constant infallible teaching of the Church, based on the words of Christ (that the gates of Hell never prevail), on the indefectibility of the Church. No long explanation is needed. If you would like to review the teachings, they are on this page.
Ron,
I was always under the belief that the “New Mass” came about by the council of Vatican II. In my research, there seems to be documents stating that the “Parish Worship Program” was the driving force for this change. On the day the Mass changed it was not the decrees of the Council but the desires of the liturgy commentators that were implemented.
Can you please give me some clarification.
Thanks-in-Advance and God Bless,
Jim Belcher
The Novus Ordo was the result of Vatican II, as the impetus for the change, and the successive Popes, who contributed to the development of that form of the Mass. The details of discipline approved by either/both a Council or Pope(s) do not matter. Those who oppose the Novus Ordo try to find things to complain about in the details, as they do with Vatican II and the election of Francis. But this is irrelevant. The approval of the Mass by the Roman Pontiff for the Church guarantees that it is free from every grave error.
Sometimes errors occur at particular Novus Ordo Masses, errors that are unfortunate. But these are exaggerated in that any such error, anywhere in the world, can become known and spread to the whole Church via the internet — making it seem as if such errors are common, when they are not. These errors are not due to the approved form of the Mass, but due to the failings of sinners. So the solution is to address sin, not to reject an approved form of the Mass.