It doesn't say much for your advanced theological skills of finding truth when a total dumbell like me can find it.
Never, not once, not ever, did I EVER assert "that the Sacrament of Baptism sufficed for membership in the Church."
If you found one theologian who said that, he's wrong, but if you actually did look, you would've found a lot more than only one.
All this is to say you have no clue what my (Catholic) ecclesiology is.
You're either lying or so ignorant / stupid that you didn't even understand what you were saying (either one is possible). You have regularly argued that Baptism suffices for membership in the Church, citing Father Wathen (your rule of faith) along those lines. We've spent countless threads arguing about it, where you even tried to explain away Pope Pius XII as saying the opposite of what he actually taught, namely, that heresy and schism sever membership in the Catholic Church.
If I had the time, I would find all your nonsense with the CI search engine, but you have been making this absurd claim for YEARS now.
Not to mention that you contradict yourself in this idiotic post. First you deny that you ever said that Baptism sufficed for membership, but then you claim that there are many theologians who hold this opinion (that you now claim you don't hold). No, there was exactly one theologian, and Msgr. Fenton named his name and explained that his position died with him.
Your other stupidity is the argument that the Magisterium is inerrant, but then you claim that any errors taught by the Pope are simply not "Magisterium". So if the Pope teaches and it happens to be true, then it's Magisterium, but if a Pope teaches something erroneous, then it's not Magisterium. So you defined Magisterium as the true things that a Pope happens to teach in his official teaching capacity, a definition that absolutely no one holds.
Really, your nonsense is mind-numbing, and it's astonishing that anyone takes your idiocy seriously.