Defending sensus fidelium and its infallibility


Why is a doctrine true because a lot of early Christians believed it? Before I became Catholic, but was a Protestant looking in and seeing that early Christians believed a lot of these Catholic things, I had this general idea that these things were revealed directly by God. It was good enough for me to convert (that and finding that EENS and that I was vincibly ignorant), so I did. Now, though, I don’t quite get how you have these beliefs that can’t be proved directly by Scripture or observation such as purgatory (which makes perfect logical sense, and I seek indulgences often). What I want to know is when the belief in (let’s use purgatory for a concrete example) crops up and where the belief comes from (inspiration by God?). For the particular instance of purgatory: I’m not interested in knowing that pre-Christ Jews believed it (cf Maccabbees); I’m interested in knowing why they believed it. Is that just lost to history? For the sake of defense (since a Protestant interloper will likely reject these), let’s disregard private revelations and apparitions.

This is two questions:
How is sensus fidelium infallible?
How does a particular infallible belief that can’t be proven by experiment or not given directly by public revelation come to be?


Where does Scripture tell us that all beliefs must be proven directly from Scripture?

It’s important to understand the term “sensus fidelium”. It means all the faithful (not just the laity). So, when the entire Church (including the magisterium) believes something, then we can say that the sensus fidelium is engaged and is believing infallibly.

By virtue of the teaching of the magisterium, whom we believe to be protected from error by the Holy Spirit in matters of faith and morals.

Or… do you mean the process?


I’m not asking how the idea is made true, but rather where the idea comes from. For the purpose of this thread, we’ll use purgatory. How did the first person who talked about purgatory know that it existed? Revelation? Vision? Visitation?

I guess this is coming from that I recently found out that we don’t believe that the Bible was dictated word-for-word by God (am former Protestant). I’m wondering how knowledge about things that we can’t know is obtained (where does the magisterium get its facts from?)


Belief in Purgatory is in the Bible. Read Second Maccabees 12:45.Also First Corinthians 3:11-15.


Don’t forget that Jesus taught His Disciples much, MUCH more than what is recorded in Scripture. And then those Apostles taught their disciples through oral teaching much, MUCH more than what is recorded as well, and so on and so on.

Faithful men, brought up in the Jewish faith, were taught how Jesus fulfilled that Faith, and then it was passed down to more faithful men, both Jewish and Gentile.

So the Apostles would have understood the Jewish roots of the idea of Purgatory, had their understanding expanded by the Holy Spirit, and then passed that down. Also, the Holy Spirit guided those faithful priests and bishops in the first centuries as doctrine and dogma was explained, written, and codified.

Purgatory didn’t just pop up out of nowhere in the Middle Ages. In The Fathers Know Best, starting on page 385, Jimmy Akin explains how the Jews believed in purification after death and Orthodox Jews to this day believe this and pray for the souls of their loved ones.

The belief in purification after death, whether it took time or happened instantly, was commonly believed by the very early Church Fathers. Akin quotes many of them, like St. Cyril of Jerusalem, St. Gregory of Nyssa, and St. John Chrysostom, so we can prove that the belief in Purgatory wasn’t something that Catholics just made up out of nowhere. It’s part of a Tradition of Faith that goes back before the Incarnation.

This is how all doctrine developed, not just Purgatory. Faithful men, inspired and guided by the Holy Spirit, passed down the depository of Faith for future generations, clarifying and explaining it further as their understanding of it deepened over the generations.


Sensus fidelium is that gift by which the members of the Church come to agree with her teachings. It’s not about developing beliefs or doctrine.

How do you know that the teaching on purgatory, for example, was not given by public revelation? Scripture was never intended to serve as a catechism.
"Jesus did many other things as well. If every one of them were written down, I suppose that even the whole world would not have room for the books that would be written." John 21:25
"So then, brothers and sisters, stand firm and hold fast to the teachings we passed on to you, whether by word of mouth or by letter." 2 Thess 2:15

Aside from that, every ancient Church that I know of, whether in the east or the west, regardless of isolation from each other, holds to some sort of doctrine regarding a place or state of final purification before entrance into heaven.


OK, so I already mentioned I’m aware of Maccabees, but how, in the case of the Jews, did they know about the final purification? Who told them? Who had the vision or the apparition? To whom did God reveal it? Is this something knowable?

I am not asking whether a belief was believed at the time. I’m asking how they came across that belief.
For example, I believe that there exist small particles (atoms) made up of smaller particles because appropriate authorities told me. Those authorities know because they received this knowledge from appropriate authorities, who in turn received this knowledge from scientists who found this knowledge by experiment.
However, experiment is not the only way to get knowledge. For example, I do not know what is going on in my friend’s head, but he tells me that he is planning to write a simple chatbot in C++ and starts detailing the “personality” of the chatbot, then I know what the chatbot will be like, not because I have used the chatbot (this wouldn’t be possible, because it hasn’t been written yet), but because the friend told me. I know the friend has Netbeans (has the means to do it), likes to make text-based programs (would probably do it), and hasn’t lied to me about his programs before (is trustworthy).
Tradition (with a small t) is also a way to get knowledge, but tradition seems to be just experiment that has no singular discoverer (you can make sourdough like this, you can’t eat that berry because it’s poisonous, the deer like to come to this spot).
There is likely some other way of obtaining knowledge that I’m probably forgetting. If that method may have been how the Jews found out about purgatory, include that. How did the Jews obtain this knowledge?


Even as a former Protestant, I never believed that God dictated the Bible word for word, but rather writers, as inspired by the Holy Spirit, wrote. It’s like He allowed them to write in their own voice & style but with a message from God.


Guys, I’m having an epistemological crisis here, help me out.


I can only assume that it was revealed to them by God. Perhaps He revealed it to the prophets.


I think that the ancient Christian view would be more in line with what Eastern Catholics and Eastern and Oriental Orthodox Christians believe.

Purgatory in the East is called Hades and it’s a place of gloom and waiting.

Purgatory is more of a Western development.

St Perpetua is one of the early Saints used to support Purgatory and it’s early Christian heritage.

Interestingly enough the narrative of her story about her younger unbaptized brother spending time in Purgatory more closely resembles Hades.

I personally do not believe the book of Maccabees is a good defense for Purgatory or Hades but I do think it is a good defense for the practice of praying and making reparation for the deceased.


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