What is at issue is whether any church is ever divinely protected from doctrinal error, not moral error, under certain conditions.
Elsewhere he described one component of this:
“In Catholic theology, it is not even a matter of dispute that the definition of 1870 [of “papal infallibility”] applies to Pius IX’s definition of the Immaculate Conception in 1854, and indeed to every papal ratification of conciliar dogmatic decrees set forth to bind the whole Church, going back to the 4th century.
Other Roman Catholics say rather, “Yes, it is a matter of dispute”:
“How many times has the pope taught ex cathedra, or ‘from the chair’ of Peter? How many ex cathedra papal statements have there been, and what are they? . . . Different Roman Catholic apologists have asserted very divergent numbers of infallible papal statements. . . . It depends on which apologist you ask….
Of course, the “apologists you ask” aren’t the standard, but the fact that even self-described “conservative” Roman Catholics disagree is telling [never mind all those “Liberal” Catholics who may or may not be real Catholics].
You all have “the one true teaching”, which is infallibly correct, but even on this absolutely fundamental question, the question which you say shows beyond a shadow of a doubt that Roman Catholics may absolutely and infallibly make the distinction between “divine revelation and human opinion”, on this most fundamental of foundations, there is confusion.
What good on earth is the “infallible Magisterium” if it can’t answer this fundamental question? What good is having the “basis for making a principled distinction between divine revelation and human opinion”, if even that “basis” doesn’t work out in real life?