One might think, either through ignorance or false humility, that because we are not the pope (or at least a bishop), we should not “set ourselves up in judgment” regarding whether the conciliar hierarchy is teaching the truth or not, or whether the conciliar hierarchy’s teachings are consistent with the traditional teaching of the Church. One might wrongly think that, failing to believe whatever the current hierarchy tells us, shows a “Protestant mentality”, i.e., deciding for ourselves what to believe.
St. Paul writes to his converts to whom he taught the Faith:
Though we, or an angel from heaven, preach a Gospel to you besides that which we have preached to you, let him be anathema.
And St. Paul emphasizes this point by immediately repeating it:
As we said before, so now I say again: If anyone preach to you a Gospel, besides that which you have received, let him be anathema.
But the Galatians might have objected, why should we believe your Gospel on your first visit to Galatia and not an eventually different one on your second? St. Paul immediately gives a first reason:
The Gospel which was preached by me is not according to man. For neither did I receive it of man, nor did I learn it, but by the revelation of Jesus Christ.
And St Paul confirms this by narrating how little contact he had with those who might have taught him (viz., the other Apostles) before he began preaching. Galatians, 1:15-19. The Galatians could verify the facts and St. Paul swears an oath to the Galatians that he is not lying. Galatians, 1:20.
He gives a second reason a little later, which is the miracles and experience of the Holy Ghost [Galatians, 3:2-5] that the Galatians themselves had witnessed as the direct result of the preaching of St. Paul’s first visit.
Thus, St. Paul confirms that God taught him the Gospel which he had already taught to the Galatians. St. Paul tells them that they can, and they must, distinguish it from false doctrine. Each Catholic has this duty.
When the shepherd turns into a wolf, the first duty of the flock is to defend itself. As a general rule, doctrine comes from the bishops to the faithful, and it is not for the faithful, who are subjects in the order of Faith, to pass judgment on their superiors. But every Christian, by virtue of his title to the name Christian, has not only the necessary knowledge of the essentials of the treasure of Revelation, but also the duty of safeguarding them. The principle is the same, whether it is a matter of belief or conduct, that is, of dogma or morals. Treachery such as that of Nestorius is rare in the Church; but it can happen that, for one reason or another, pastors remain silent on essential matters of faith. The true children of Holy Church at such times are those who walk by the light of their baptism, not the cowardly souls who, under the specious pretext of submission to the powers that be, delay their opposition to the enemy in the hope of receiving instructions which are neither necessary nor desirable.
The Liturgical Year, Vol. IV, Dom Guéranger; see the entry for the Feast of St. Cyril of Alexandria, February 9th (emphasis added).
Here is another authority: St. Vincent Lerins, in his Commonitorium:
What then should a Catholic do if some part of the Church were to separate itself from communion with the universal Faith? What other choice can he make but to prefer to the gangrenous and corrupted member, the whole of the body that is sound. And if some new contagion were to try to poison no longer a small part of the Church, but all of the Church at the same time, then he will take the greatest care to attach himself to antiquity which, obviously, can no longer be seduced by any lying novelty.
Emphasis added. Note that St. Vincent gives this rule to all Catholics, not only to the bishops or doctors of theology.
Humans can understand the Catholic Faith, though not perfectly as God does. Our Faith is presented as a series of statements in each of which a predicate is said of a subject. Even though the faithful Catholic cannot prove by natural reason, this link (i.e., connection) between the subject and predicate, he knows by Faith that the link exists and thus, that the opposite statement must be false.
If one were to (wrongly) say that a Catholic is forbidden to compare current teachings of the hierarchy, with the consistent teaching of the Church of all time, this would mean that a Catholic is forbidden to understand what he is saying (and believing) when he is professing his Faith. This position would instead substitute a blind obedience which accepts a mere formula of sounds – devoid of meaning – when professing the Faith. The Catholic Church has never professed such nominalism. Instead, the Church wants (and requires) Her children to understand the Faith, not merely memorize sounds or words by rote.