22. Now, as the Apostle Paul urges, this unanimity ought to be perfect. Christian faith reposes not on human but on divine authority, for what God has revealed "we believe not on account of the intrinsic evidence of the truth perceived by the natural light of our reason, but on account of the authority of God revealing, who cannot be deceived nor Himself deceive."(24) It follows as a consequence that whatever things are manifestly revealed by God we must receive with a similar and equal assent. To refuse to believe any one of them is equivalent to rejecting them all, for those at once destroy the very groundwork of faith who deny that God has spoken to men, or who bring into doubt His infinite truth and wisdom. To determine, however, which are the doctrines divinely revealed belongs to the teaching Church, to whom God has entrusted the safekeeping and interpretation of His utterances. But the supreme teacher in the Church is the Roman Pontiff. Union of minds, therefore, requires, together with a perfect accord in the one faith, complete submission and obedience of will to the Church and to the Roman Pontiff, as to God Himself. This obedience should, however, be perfect, because it is enjoined by faith itself, and has this in common with faith, that it cannot be given in shreds; nay, were it not absolute and perfect in every particular, it might wear the name of obedience, but its essence would disappear. Christian usage attaches such value to this perfection of obedience that it has been, and will ever be, accounted the distinguishing mark by which we are able to recognize Catholics. Admirably does the following passage from St. Thomas Aquinas set before us the right view: "The formal object of faith is primary truth, as it is shown forth in the holy Scriptures, and in the teaching of the Church, which proceeds from the fountainhead of truth. It follows, therefore, that he who does not adhere, as to an infallible divine rule, to the teaching of the Church, which proceeds from the primary truth manifested in the holy Scriptures, possesses not the habit of faith; but matters of faith he holds otherwise than true faith. Now, it is evident that he who clings to the doctrines of the Church as to an infallible rule yields his assent to everything the Church teaches; but otherwise, if with reference to what the Church teaches he holds what he likes but does not hold what he does not like, he adheres not to the teaching of the Church as to an infallible rule, but to his own will."(25)
23. "The faith of the whole Church should be one, according to the precept (1 Cor. 1:10): "Let all speak the same thing, and let there be no schisms among you"; and this cannot be observed save on condition that questions which arise touching faith should be determined by him who presides over the whole Church, whose sentence must consequently be accepted without wavering. And hence to the sole authority of the supreme Pontiff does it pertain to publish a new revision of the symbol, as also to decree all other matters that concern the universal Church."(26)
24. In defining the limits of the obedience owed to the pastors of souls, but most of all to the authority of the Roman Pontiff, it must not be supposed that it is only to be yielded in relation to dogmas of which the obstinate denial cannot be disjoined from the crime of heresy. Nay, further, it is not enough sincerely and firmly to assent to doctrines which, though not defined by any solemn pronouncement of the Church, are by her proposed to belief, as divinely revealed, in her common and universal teaching, and which the Vatican Council declared are to be believed "with Catholic and divine faith."(27) But this likewise must be reckoned amongst the duties of Christians, that they allow themselves to be ruled and directed by the authority and leadership of bishops, and, above all, of the apostolic see. And how fitting it is that this should be so any one can easily perceive. For the things contained in the divine oracles have reference to God in part, and in part to man, and to whatever is necessary for the attainment of his eternal salvation. Now, both these, that is to say, what we are bound to believe and what we are obliged to do, are laid down, as we have stated, by the Church using her divine right, and in the Church by the supreme Pontiff. Wherefore it belongs to the Pope to judge authoritatively what things the sacred oracles contain, as well as what doctrines are in harmony, and what in disagreement, with them; and also, for the same reason, to show forth what things are to be accepted as right, and what to be rejected as worthless; what it is necessary to do and what to avoid doing, in order to attain eternal salvation. For, otherwise, there would be no sure interpreter of the commands of God, nor would there be any safe guide showing man the way he should live.
Sapientiae Christianae, Pope Leo XIII