that a man CANNOT take the purported Roman Pontiff as a rule of faith, or the practice thereof. Is this not a frightening fact?
Not at all. God is more powerful than the pope, and His religion cannot be corrupted. Under proper obedience, corruption or evil in any man, even the pope, is powerless against the incorruptible faith.
If the church and the true faith depended upon the virtue of the men who hold it's offices to exist and survive, there would (humanly speaking) surely be no church today. But because it is a divinely instituted thing, no amount of human corruption, even of it's authorities, can possibly corrupt, alter or kill it. The faith is not given the popes to change, but to transmit. The Catholic is therefore correct who recognizes BOTH... the divine grace and life of the true faith and it's incorruptible nature, AND the fallibility of every man (even the pope when he is not willfully exercising his infallibility).
The Catholic of a balanced and prudent mind will not be at all shocked (or at least not much) if the pope sins, or sins grievously. They know the pope sins. He's human. They know also not to follow him into sin. Such a Catholic has the privilege of being founded upon a rock, not tossed to and fro with the waves of confusion and uncertainty. He will follow the pope where the pope is right and where it is all right to follow him, and disobey him (in obedience to God) where the pope is wrong and it would be wrong to follow him. He needn't deny the office of the man because the man might be bad. (He would never dare judge the man, as only God can do.) The Catholic who has not neglected his own moral and theological education knows his faith well enough to know what it IS, and what it is NOT. He has good sense enough (by the help of God) to keep his own bearings regardless of what the Pope as man is, and the humility to obey when the man is right.
The king, even if bad, is still the king. The martyrs who died under the roman emperors, I'm sure, never once denied that the emperors were the emperors simply because they were pagan and wicked. Instead, they acknowledged by laying down their lives that his authority came from God, and that the office was what it was, regardless of the rottenness of the man in it. So, too, the sensible Catholic knows the pope is the pope, for better or for worse, and will for the love of God obey him when he is right, and in anything he can morally do so, and for the love of God again, disobey where he must, even as the martyrs obeyed the emperors in dying, but NOT in offering sacrifice to false gods. We can obey the pope in anything not contrary to God, even if we can't follow this new religion. He still carries the authority of God as pope, however good or bad he is as a man.