Institutional infidelity

1. Hypothetically, what would the magisterium have to do for devout Catholics (or Catholic apologists) to conclude that the Roman Catholic church never was the one true church founded by Jesus Christ? Can the magisterium ever do anything, in principle or practice, to discredit Roman Catholicism? 

Put another way, how do we distinguish between a faithful church and a faithless church? What's the standard of fidelity? 

2. In my observation, Catholics take the position that the pope can't change dogma. The pope can't change the deposit of faith. The pope can't elevate a heresy to the status of dogma. The pope can't make a moral teaching that contradicts natural law de fide doctrine. However, the hierarchy can say or do anything short of that without discrediting Roman Catholicism. 

So in theory, if the pope, speaking ex cathedra, were to change doctrine, change the deposit of faith, dogmatize heresy, teach contrary to natural law, his action would show that the Roman Catholic church was never the church founded by Jesus Christ.

However, that's paradoxical, and a tenacious Catholic apologist might find a loophole by saying that if a pope were to do that, it wouldn't disprove Catholicism; rather, it would disprove the claim that he was speaking ex cathedra. But there are two related problems with that defense:

i) If a pope cannot change dogma even when he intends to speak ex cathedra, even when he uses ex cathedra formulas, then it's impossible to verify when or if a pope is speaking ex cathedra. If papal intent and ex cathedra formulas are insufficient criteria, then there's no way to verify an ex cathedra pronouncement.

ii) It renders Catholicism unfalsifiable, which means that even if Catholicism is actually wrong, Catholics are never be in a position to know it's wrong. In that event, they have an unshakable commitment to a false religion.  

3. In addition, this defines fidelity or infidelity in exclusively abstract, impersonal terms. Fidelity or infidelity is restricted to propositions. The members of the magisterium can say or to anything consistent with institutional fidelity so long as the dogmatic statements are faithful to the deposit of faith. It reduces fidelity to verbal formulas.  If every pope taught heresy, but not formally or officially (i.e. dogma, de fide, ex cathedra), the Catholic church would still be a faithful church. If every pope, cardinal, bishop, and priest was an active sodomite, the Catholic church would still be a faithful church. 

But a fundamental problem with that restrictive concept of fidelity is that, of necessity, fidelity has a personal dimension. It isn't just words on a page. To be faithful is to be obedient in thought word and deed. Fidelity in what we believe as well as fidelity in how we live. Fidelity to God. A living relationship of life and mind between Christians and their God. If members of a church are overwhelmingly faithless in what they believe and how they act, then that's a faithless church. 

For instance, a creed is at best a standard of fidelity, not a substitute for fidelity. A benchmark for what to believe and how to behave. 

Assuming a creed is true, if a denomination refuses to enforce the creed, constantly teaches contrary to the creed, constantly disregards the creed in practice, then the creed is insufficient to make that a faithful denomination. There must be a living connection between what's on paper and what's in the heart. Otherwise, it's like saying a church is faithful so long as it has an infallible creed in a safe, that no one has ever read.