This argument from redeemed zoomer's twitter account. What is the catholic response to it?

How can you infallibly know whether the true church is the Catholic Church or the Orthodox Church?

If you can use fallible historical reason to determine that, then I can use fallible historical reason to determine the canon of Scripture

  • 1
    Humans are fallible. Scientists know this, and so don't claim that their theories are Truth. (Hypotheses stand or fall on how well they conform with observation. If a hypothesis conforms well with observation, it becomes a Theory; Laws are mathematical formula that successfully predict reality.) Unfortunately, our usage of the word "theory" is pretty sloppy, so the strict definitions of Hypothesis and Theory are seldom followed.
    – RonJohn
    Commented Apr 12 at 3:17
  • 6
    Not only that: How can you infallibly know that you infallibly know? "It's turtles all the way down!" Commented Apr 12 at 11:36
  • 1
    The point is: faith is not about knowing, it is about believing.
    – Florian F
    Commented Apr 12 at 18:47

5 Answers 5


There is no logical philosophical argument that is strong enough to convince someone who is not willing to be convinced. I am a member of the Catholic clergy, so it will come as no surprise that I believe, maybe even "know" the Catholic Church is the "true church". The second Vatican council talks about this with much more nuance, but for the sake of this question that is not really important. The problem is that any proof, and "infallibly knowing" could be defined as "proof", requires some axioms.

The willingness to be convinced can also be described as the sharing of accepted axioms. If for example you would accept the axioms that describe what books are in the Bible, and the axiom that everything in the Bible is true, you get a completely different argument than when you do not accept those axioms.

So like atheist will be most happy to point out with most if not all religious claims, the arguments for a claim are most likely not accepted because of a different accepted set of axioms. In other words, the answer to your question is: you cannot unless you already believe that.


Regarding Catholicism vs Orthodoxy

I always like to reference historical timelines when discussing these types of conflicts. While the X post which you cited identifies history as fallible (and rightfully so), there is still lots of information offered by history which is factually sound.

As we know, the Orthodox churches were the offspring of the Great Schism of 1054, which took place over a thousand years after the birth of the Church, and was caused by some significant differences in theological beliefs. For me, this fact alone is sufficient for belief in the "One True Church," as I remember Christ's promise to Peter: "Upon this rock I will build my church, and the gates of hell shall not prevail against it." (Matthew 16:18) I have faith that the Holy Spirit would not allow Christ's Church to exist in such significant error for over a thousand years, just to be split into two as the solution to said error - especially after Christ gave His very life for that church! However, similar to ABM K's answer, there's a theme of axioms which may sway one's conclusions on this matter.

The General Issue of Infallibility

Because God gives man a free will and intellect, there will naturally always be Christians who "give themselves over" to the service of devil rather than God. To clarify, many may do this without realizing it - in other words, they may submit to the devil's work without ever declaratively expressing it. Nevertheless, this pattern can be seen since the beginning of the time.

I often like to madidate on the vision of Pope Leo XIII, which was the inspiration behind his formation of the St. Michael prayer. In this vision, Satan is seen conversing with Christ and claiming, "I can destroy your Church... [if you grant me] a greater power over those who will give themselves over to my service." If you consider the example of the selling of indulgences, it clearly demonstrates the presence of evil Christians since the earliest centuries. It's a clear sign that the enemy has been working to infiltrate the Church since her conception.

Regarding your question, I think it's very important to understand where the Church draws the line regarding infallibility. It has been clearly demonstrated throughout history (and even today) that every individual within the Church is very much not infallible. As such, the Church has never laid claim to infallibility as an institution. Rather, the claim to infallibly lies in official teachings on matters of faith and morals (i.e. doctrine and dogma), which are formulated through ecumenical councils. Thus, no evidence can be presented against this claim unless it demonstrates error in official church teaching. At the same time, it is difficult to find evidence to support the Church's claim of infallible teaching without operating on a certain set of axioms.

On that note, I find AFraizer's argument to be flawed, as it is addressing corrupt practices of individuals rather than official teachings from the Church as a whole. That is not to say that those evil practices were few and far between, but only that they were not officially endorsed by Church doctrine. Similarly, we have other forms of corruption within the church today which can be found throughout the world (mostly the United States), but these are the results of corrupted individuals and not of Church teachings.

In conclusion, while I do believe the Church's teaching to be infallible, I am not aware of any way to either prove nor disprove this infallibility with science, logic, or reason.

  • A counterpoint to most of this would probably be that God allowed His chosen and promised Israel to be taken into Babylon for 70ish years, with many more broken, lean years before it (the kingdom of Israel destroyed over 100 years earlier). Or indeed the like 1800 year period of growing Jewish separation from Israel until at least recent times. Commented Apr 13 at 7:37
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    How were the orthodox churches the offspring of the schism? Surely it's the other way around since it was the Western, now "Catholic" church that introduced something new, Fillioque, thereby moving away from the original, orthodox faith. So the Catholics were the "offspring" of the schism with the Orthodox continuing with what they had before. I am not implying either one is more correct than the other, I personally do not accept either of their belief systems, but historically speaking, it's the Catholics that broke away.
    – terdon
    Commented Apr 13 at 15:04
  • @JeopardyTempest I had actually considered this point myself. My reasoning is that Israel was the chosen people, but not not the church. They lived in error because the Kingdom of Heaven (the the Church) had not yet been established on earth to govern them. God provided us with the fullness of revelation in Christ's human ministry, and established his Church (the Kingdom) under the guidance of the Spirit to teach that revelation. Christ died that His Church might live, and He gave Spirit that the Church would live in holiness (as a whole). I hope that makes sense. Commented Apr 13 at 16:17
  • @terdon When I say Orthodoxy was the offspring of the schism, I mean that, as an institution, it did not exist prior to the schism, but was established as a result thereof. I make the claim that Church which existed before the schism was the Catholic Church because it was the Apostolic Church, and because after the schism the Apostolic Church remained the Catholic Church and not the Orthodox. Commented Apr 13 at 16:20
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    @terdon I stand corrected. It would appear that both the Catholic and the Orthodox Churches are apostolic. However, the Orthodox Church was lead by Michael Cerularius and has no papacy, while the Catholic Church remained under Pope Leo IX. In other words, the papacy was part of the One Church for 1000+ years, and after the schism the only church with a pope was the Catholic Church. It's hard to say which church was the "offspring" because while the Catholics added something, the Orthodox removed something which had been part of the church since the beginning. Commented Apr 14 at 2:44

How can we infallibly know that the Catholic Church is infallible?

Before going on, it is of upmost importance to understand what the Catholic Church teaches about the doctrine of infallibility. This dogma is not magical and is invoked under a very strict definition of rules. Without this knowledge and understanding one can not know how the Church is actually infallible.

True meaning of infallibility

It is well to begin by stating the ecclesiological truths that are assumed to be established before the question of infallibility arises. It is assumed:

  • that Christ founded His Church as a visible and perfect society;

  • that He intended it to be absolutely universal and imposed upon all men a solemn obligation actually to belong to it, unless inculpable ignorance should excuse them;

  • that He wished this Church to be one, with a visible corporate unity of faith, government, and worship; and that

in order to secure this threefold unity, He bestowed on the Apostles and their legitimate successors in the hierarchy — and on them exclusively — the plenitude of teaching, governing, and liturgical powers with which He wished this Church to be endowed.

Proof of the Church's infallibility

That the Church is infallible in her definitions on faith and morals is itself a Catholic dogma, which, although it was formulated ecumenically for the first time in the Vatican Council, had been explicitly taught long before and had been assumed from the very beginning without question down to the time of the Protestant Reformation. The teaching of the Vatican Council is to be found in Session III, cap. 4, where it is declared that "the doctrine of faith, which God has revealed, has not been proposed as a philosophical discovery to be improved upon by human talent, but has been committed as a Divine deposit to the spouse of Christ, to be faithfully guarded and infallibly interpreted by her"; and in Session IV, cap. 4, where it is defined that the Roman pontiff when he teaches ex cathedra "enjoys, by reason of the Divine assistance promised to him in blessed Peter, that infallibility with which the Divine Redeemer wished His Church to be endowed in defining doctrine regarding faith and morals". Even the Vatican Council, it will be seen, only introduces the general dogma of the Church's infallibility as distinct from that of the pope obliquely and indirectly, following in this respect the traditional usage according to which the dogma is assumed as an implicate of ecumenical magisterial authority. Instances of this will be given below and from these it will appear that, though the word infallibility as a technical term hardly occurs at all in the early councils or in the Fathers, the thing signified by it was understood and believed in and acted upon from the beginning. We shall confine our attention in this section to the general question, reserving the doctrine of papal infallibility for special treatment. This arrangement is adopted not because it is the best or most logical, but because it enables us to travel a certain distance in the friendly company of those who cling to the general doctrine of ecclesiastical infallibility while rejecting the papal claims. Taking the evidence both scriptural and traditional as it actually stands, one may fairly maintain that it proves papal infallibility in a simpler, more direct, and more cogent way than it proves the general doctrine independently; and there can be no doubt but that this is so if we accept as the alternative to papal infallibility the vague and unworkable theory of ecumenical infallibility which most High-Church Anglicans would substitute for Catholic teaching. Nor are the Eastern schismatical Churches much better off than the Anglican in this respect, except that each has retained a sort of virtual belief in its own infallibility, and that in practice they have been more faithful in guarding the doctrines infallibly defined by the early ecumenical councils. Yet certain Anglicans and all the Eastern Orthodox agree with Catholics in maintaining that Christ promised infallibility to the true Church, and we welcome their support as against the general Protestant denial of this truth.

Proof from Scripture

  1. In order to prevent misconception and thereby to anticipate a common popular objection which is wholly based on a misconception it should be premised that when we appeal to the Scriptures for proof of the Church's infallible authority we appeal to them merely as reliable historical sources, and abstract altogether from their inspiration. Even considered as purely human documents they furnish us, we maintain, with a trustworthy report of Christ's sayings and promises; and, taking it to be a fact that Christ said what is attributed to Him in the Gospels, we further maintain that Christ's promises to the Apostles and their successors in the teaching office include the promise of such guidance and assistance as clearly implies infallibility. Having thus used the Scriptures as mere historical sources to prove that Christ endowed the Church with infallible teaching authority it is no vicious circle, but a perfectly legitimate logical procedure, to rely on the Church's authority for proof of what writings are inspired.

  2. Merely remarking for the present that the texts in which Christ promised infallible guidance especially to Peter and his successors in the primacy might be appealed to here as possessing an a fortiori value, it will suffice to consider the classical texts usually employed in the general proof of the Church's infallibility; and of these the principal are:

  • Matthew 28:18-20;

  • Matthew 16:18;

  • John 14, 15, and 16;

  • I Timothy 3:14-15; and

  • Acts 15:28 sq.

  • Matthew 28:18-20

In Matthew 28:18-20, we have Christ's solemn commission to the Apostles delivered shortly before His Ascension: "All power is given to me in heaven and in earth. Going therefore, teach ye all nations; baptizing them in the name of the Father, and of the Son, and of the Holy Ghost; teaching them to observe all things whatsoever I have commanded you: and behold I am with you all days, even to the consummation of the world." In Mark 16:15-16, the same commission is given more briefly with the added promise of salvation to believers and the threat of damnation for unbelievers; "Go ye into the whole world, and preach the gospel to every creature. He that believeth and is baptized shall be saved; but he that believeth not shall be condemned."

Proof from Tradition

If, during the early centuries, there was no explicit and formal discussion regarding ecclesiastical infallibility as such, yet the Church, in her corporate capacity, after the example of the Apostles at Jerusalem, always acted on the assumption that she was infallible in doctrinal matters and all the great orthodox teachers believed that she was so. Those who presumed, on whatever grounds, to contradict the Church's teaching were treated as representatives of Antichrist (cf. 1 John 2:18 sq.), and were excommunicated and anathematized.

  • It is clear from the letters of St. Ignatius of Antioch how intolerant he was of error, and how firmly convinced that the episcopal body was the Divinely ordained and Divinely guided organ of truth; nor can any student of early Christian literature deny that, where Divine guidance is claimed in doctrinal matters, infallibility is implied.

  • So intolerant of error was St. Polycarp that, as the story goes, when he met Marcion on the street in Rome, he did not hesitate to denounce the heretic to his face as "the firstborn of Satan". This incident, whether it be true or not, is at any rate thoroughly in keeping with the spirit of the age and such a spirit is incompatible with belief in a fallible Church.

  • St. Irenaeus, who in the disciplinary Paschal question favoured compromise for the sake of peace, took an altogether different attitude in the doctrinal controversy with the Gnostics; and the great principle on which he mainly relies in refuting the heretics is the principle of a living ecclesiastical authority for which he virtually claims infallibility. For example he says: "Where the Church is, there also is the Spirit of God, and where the Spirit of God is there is the Church, and every grace: for the Spirit is truth" (Adv. Haer. III, xxiv, 1); and again, Where the charismata of the Lord are given, there must we seek the truth, i.e. with those to whom belongs the ecclesiastical succession from the Apostles, and the unadulterated and incorruptible word. It is they who . . . are the guardians of our faith . . . and securely [sine periculo] expound the Scriptures to us" (op. cit., IV xxvi, 5).

  • Tertullian, writing from the Catholic standpoint, ridicules the suggestion that the universal teaching of the Church can be wrong: "Suppose now that all [the Churches] have erred . . . [This would mean that] the Holy Spirit has not watched over any of them so as to guide it into the truth, although He was sent by Christ, and asked from the Father for this very purpose — that He might be the teacher of truth" (doctor veritatis — "De Praescript", xxxvi, in P.L., II, 49).

  • St. Cyprian compares the Church to an incorruptible virgin: Adulterari non potest sponsa Christi, incorrupta est et pudica (De unitate eccl.). It is needless to go on multiplying citations, since the broad fact is indisputable that in the ante-Nicene, no less than in the post-Nicene, period all orthodox Christians attributed to the corporate voice of the Church, speaking through the body of bishops in union with their head and centre, all the fullness of doctrinal authority which the Apostles themselves had possessed; and to question the infallibility of that authority would have been considered equivalent to questioning God's veracity and fidelity. It was for this reason that during the first three centuries the concurrent action of the bishops dispersed throughout the world proved to be effective in securing the condemnation and exclusion of certain heresies and maintaining Gospel truth in its purity; and when from the fourth century onwards it was found expedient to assemble ecumenical councils, after the example of the Apostles at Jerusalem, it was for the same reason that the doctrinal decision of these councils were held to be absolutely final and irreformable. Even the heretics, for the most part recognized this principle in theory; and if in fact they often refused to submit, they did so as a rule on the ground that this or that council was not really ecumenical, that it did not truly express the corporate voice of the Church, and was not, therefore, infallible. This will not be denied by anyone who is familiar with the history of the doctrinal controversies of the fourth and fifth centuries, and within the limits of this article we cannot do more than call attention to the broad conclusion in proof of which it would be easy to cite a great number of particular facts and testimonies.

The pope

Explanation of papal infallibility

The Vatican Council has defined as "a divinely revealed dogma" that "the Roman Pontiff, when he speaks ex cathedra — that is, when in the exercise of his office as pastor and teacher of all Christians he defines, by virtue of his supreme Apostolic authority, a doctrine of faith or morals to be held by the whole Church — is, by reason of the Divine assistance promised to him in blessed Peter, possessed of that infallibility with which the Divine Redeemer wished His Church to be endowed in defining doctrines of faith and morals; and consequently that such definitions of the Roman Pontiff are irreformable of their own nature (ex sese) and not by reason of the Church's consent" (Denzinger no. 1839 — old no. 1680). For the correct understanding of this definition it is to be noted that:

  • what is claimed for the pope is infallibility merely, not impeccability or inspiration (see above under I).

  • the infallibility claimed for the pope is the same in its nature, scope, and extent as that which the Church as a whole possesses; his ex cathedra teaching does not have to be ratified by the Church's in order to be infallible.

  • infallibility is not attributed to every doctrinal act of the pope, but only to his ex cathedra teaching; and the conditions required for ex cathedra teaching are mentioned in the Vatican decree:

  • The pontiff must teach in his public and official capacity as pastor and doctor of all Christians, not merely in his private capacity as a theologian, preacher or allocutionist, nor in his capacity as a temporal prince or as a mere ordinary of the Diocese of Rome. It must be clear that he speaks as spiritual head of the Church universal.
  • Then it is only when, in this capacity, he teaches some doctrine of faith or morals that he is infallible (see below, IV).
  • Further it must be sufficiently evident that he intends to teach with all the fullness and finality of his supreme Apostolic authority, in other words that he wishes to determine some point of doctrine in an absolutely final and irrevocable way, or to define it in the technical sense. These are well-recognized formulas by means of which the defining intention may be manifested.
  • Finally for an ex cathedra decision it must be clear that the pope intends to bind the whole Church. To demand internal assent from all the faithful to his teaching under pain of incurring spiritual shipwreck (naufragium fidei) according to the expression used by Pius IX in defining the Immaculate Conception of the Blessed Virgin. Theoretically, this intention might be made sufficiently clear in a papal decision which is addressed only to a particular Church; but in present day conditions, when it is so easy to communicate with the most distant parts of the earth and to secure a literally universal promulgation of papal acts, the presumption is that unless the pope formally addresses the whole Church in the recognized official way, he does not intend his doctrinal teaching to be held by all the faithful as ex cathedra and infallible.

It should be observed in conclusion that papal infallibility is a personal and incommunicable charisma, which is not shared by any pontifical tribunal. It was promised directly to Peter, and to each of Peter's successors in the primacy, but not as a prerogative the exercise of which could be delegated to others. Hence doctrinal decisions or instructions issued by the Roman congregations, even when approved by the pope in the ordinary way, have no claim to be considered infallible. To be infallible they must be issued by the pope himself in his own name according to the conditions already mentioned as requisite for ex cathedra teaching.

After all this has been explained and understood how can we infallibly know whether the true church is the Catholic Church?

The true faithful must be docile to the inspirations and prompting of the Holy Spirit within the Church. The problem here is that the faithful of other denominations will in themselves believe the exact same way about their own denominations. The Catholic Church has never changed her stances on questions of faith and morals. For example the Catholic Church teaches that abortion is immoral and cannot alter this teaching. The same is true of a only male priesthood. The earnest stability of of Church doctrine is a clear indication of the infallible nature of the one and true Church of Jesus Christ, even though some of her ministers and faithful may be living lives contrary to the ways of the Gospel.

In the end, the Church remains the Bride of Christ and is infallible since her conception, regardless of how many corrupt members of the Church have existed over the centuries. This could be said of many other denominations.

History has shown that when the Church is holy, she is attacked from without. When the Church is unholy, she is attacked from without and within. God knows how to purify the Church and bring back the faithful to lives of religious edification and holiness.

In the end you will either believe the Catholic Church if the true Church and is infallible or you will not. No arguments for or against this subject matter can change the opinion of others on this issue, whether on a philosophical or moral basis. Only the inspiration of the Holy Spirit is able to enlighten men’s hearts and mind in this domain.



My Roman Catholic logic is this: if God gives to the pope this power about His only Chuch, He might also give him the knowledge to decide the right thing. Thus, it is not a knowledge, only a belief.

How would you know that God exists? No one has infallable knowledge. Maybe some Saints, but you are probably not one of them. This all is our belief. This belief is what separates us from the average, very "enlightened" atheists. Because we shout to the sky in our last hope, as our ancestors do since thousands years, without even knowing, is it being heard or not.

I am nearly sure that it is being heard and also answered, but how could I prove it? And how many of us would die happily, knowing that there is something to wait us after the curtain falls? I think, only a minority even among the Christians.

There is no such thing that the Pope would be some godlike, or wizard-like being. It is not AD&D. It is just... we believe, maybe it has some reason, that he is the ruler above Peter's Grave and the same reason would likely prevent him to do some badly.

The belief of infallability is only in important moral things and in ex Cathedra statements. Anyways we are free to believe what we want to, and these often do not match what the Pope says. Only the dogmas and the ex cathedra statements are obligatory, but even these not like a law. There is no such thing that if you don't believe X, than you are expelled. It is only that we believe, believing the dogmas and the ex cathedra statements makes you a catholic.

I disagree the Pope in a lot of important questions which are not about the Life, the Universe and Everything. But I follow him in all the dogmas and the ex cathedra statements, or at least accept them.

What I disagree, I believe he is doing and saying these because he is also a politician, and he can not see a lot what we do. I do not want to politize, but I think we know a lot of terrible dangers for the Church both in the Global North and on the Global South, and honestly the realistical future is that the Christianity, together with the Catholicism, dies out in one or two centuries. Our only hope is that Jesus himself said, the Church will live forever. Note, things are not the first time look so badly, and we survived it all.

2000 years... already the Crucifixion should have destroy us, then Nero should have, then...

That is again only a belief, but honestly quite a strong belief.

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    – Community Bot
    Commented Apr 12 at 13:44

There's a basic philosophical error here:

It isn't necessary to infallibly know that an authority is infallible in order for the authority to be infallible.

Math is always correct, but math is hard, and many people, especially these days, are even skeptical that 2+2=4. However, the fact you can ask questions on SE is only because the math behind information theory is always correct.

Similarly with the Catholic church. Just because you may not be able to infallibly know the Catholic church is infallible doesn't mean the Catholic church is not infallible. Aquinas covers this distinction in his discussion of the five ways we learn about God's existence.

I answer that, A thing can be self-evident in either of two ways: on the one hand, self-evident in itself, though not to us; on the other, self-evident in itself, and to us. A proposition is self-evident because the predicate is included in the essence of the subject, as "Man is an animal," for animal is contained in the essence of man. If, therefore the essence of the predicate and subject be known to all, the proposition will be self-evident to all; as is clear with regard to the first principles of demonstration, the terms of which are common things that no one is ignorant of, such as being and non-being, whole and part, and such like. If, however, there are some to whom the essence of the predicate and subject is unknown, the proposition will be self-evident in itself, but not to those who do not know the meaning of the predicate and subject of the proposition. Therefore, it happens, as Boethius says (Hebdom., the title of which is: "Whether all that is, is good"), "that there are some mental concepts self-evident only to the learned, as that incorporeal substances are not in space." Therefore I say that this proposition, "God exists," of itself is self-evident, for the predicate is the same as the subject, because God is His own existence as will be hereafter shown (I:3:4). Now because we do not know the essence of God, the proposition is not self-evident to us; but needs to be demonstrated by things that are more known to us, though less known in their nature — namely, by effects.

  • Your "math is always correct" link s to a totally irrelevant page about information theory. Your "skeptical that 2+2=4" is some rant about "white supremacist patriarchy".
    – Florian F
    Commented Apr 14 at 9:32

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