In other words, it ultimately comes down to, ‘Because I say so,’ not ‘because the Apostles said so.’
Ultimately, if Roman doctrine contradicts what Jesus and the Prophets and Apostles actually taught—ESPECIALLY in regards to justification and worship—the Romanists CAN’T be the ‘one true church.’
And all the shouting in the universe from the usual suspects can’t change that.
And that, ladies and germs, is why there's so much shouting and vitriol coming from them especially on OPEN RF threads!
Here is a really great article on that topic Living Tradition (Viva Voce - Whatever We Say) A Repudiation of the Patristic Concept of Tradition
Notice that in Catholic theology one needs to submit to Rome to assuredly know what is of God:
RC: People cannot discover the contents of revelation by their unaided powers of reason and observation. They have to be told by people who have received in from on high. - Cardinal Avery Dulles, SJ, "Magisterium: Teacher and Guardian of the Faith, p. 72;
...the believer cannot believe in the Bible nor find in it the object of his faith until he has previously made an act of faith in the intermediary authorities..." - Catholic Encyclopedia>Tradition and Living Magisterium
.in all cases the immediate motive in the mind of a Catholic for his reception of them is, not that they are proved to him by Reason or by History, but because Revelation has declared them by means of that high ecclesiastical Magisterium which is their legitimate exponent.” — John Henry Newman, “A Letter Addressed to the Duke of Norfolk on Occasion of Mr. Gladstone's Recent Expostulation.” 8.
It was the charge of the Reformers that the Catholic doctrines were not primitive, and their pretension was to revert to antiquity. But the appeal to antiquity is both a treason and a heresy. It is a treason because it rejects the Divine voice of the Church at this hour, and a heresy because it denies that voice to be Divine... I may say in strict truth that the Church has no antiquity....Primitive and modern are predicates, not of truth, but of ourselves...The only Divine evidence to us of what was primitive is the witness and voice of the Church at this hour. — Dr. Henry Edward Cardinal Manning, Archbishop of Westminster, The Temporal Mission of the Holy Ghost: Or Reason and Revelation (New York: J.P. Kenedy & Sons, originally written 1865, reprinted with no date), pp. 227-228.
Thus, to avoid circularity,
..when we appeal to the Scriptures for proof of the Church's infallible authority we appeal to them merely as reliable historical sources... - Catholic Encyclopedia>Infallibility;
But what is the basis for Catholic assurance that there church is what it claims to be, the one true infallible church? It is because she has Rome has presumed to infallibly declared she is (if conditionally infallible), thus,
The mere fact that the Church teaches the doctrine of the Assumption as definitely true is a guarantee that it is true.” — Karl Keating, Catholicism and Fundamentalism (San Francisco: Ignatius, 1988), p. 275.
Catholic doctrine, as authoritatively proposed by the Church, should be held as the supreme law; for, seeing that [according to infallible us] the same God is the author both of the Sacred Books and of the doctrine committed to the Church, it is clearly impossible that any teaching can by legitimate means be extracted from the former, which shall in any respect be at variance with the latter.." [as the premise is false, so is the conclusion] (Providentissimus Deus;Providentissimus Deus (November 18, 1893) | LEO XIII)
We hold upon this earth the place of God Almighty..." "We have addressed to Catholic people, either collectively or individually; and above all, let them lay down for themselves as a Supreme Law, to yield obedience in all things to the teaching and Authority of the Church, in no narrow or mistrustful spirit, but with their whole soul and promptitude of will." - Praeclara Gratulationis Publicae - Papal Encyclicals