Sola Scriptura (scripture alone), as the name suggests, is the doctrine that the scriptures alone are the authority in Christianity. Any other source is irrelevant at best, outright blasphemy at worst. This doctrine is extremely easy to prove, and much to the dismay of the Catholic Church, all but impossible to attack.
There are many verses in the Bible that can be used to demonstrate the doctrine of Sola Scriptura. Others, when taken together, only serve to strengthen that case. However strong the case is, there are really only two verses you will need to prove Sola Scriptura. 2 Timothy 3:16-17.
2 Timothy 3:16-17 says "All Scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness, that the man of God may be complete, thoroughly equipped for every good work." To me, continuing this article actually seems redundant. What possible excuse can the Catholic Church make for this verse? As it turns out, not very many. Having hammered this verse to death in debates with Catholics, I have received only 3 direct responses, all of which are utterly abysmal.
1. "We believe the scriptures are inspired too."
As shown in this example, I do like to be very careful to highlight the relevant parts of the verse. It isn't the inspiration that is in dispute here. In fact, you could (though you would lose context) completely cut out verse 16 completely. What Catholics do deny is that the scriptures make the man of God complete and thoroughly equipped for every good work. There are lots of things a Catholic believes a Christian must believe that are not found in scripture, including many works they consider not just "good", but actually essential. Therefore, a Catholic cannot consistently claim to believe verse 17. There is simply no other way to interpret scripture making a man of God complete and thoroughly equipped for every good work than that the scriptures are the only authoritative source a man needs.
2. It doesn't explicitly say the words "Sola Scriptura".
The irony of this argument is that it would utterly demolish not just Catholicism, but Christianity as a whole. There are a whole host of doctrines that are not explicitly named, but are nevertheless indisputably described in the Bible. The doctrine of the Trinity, for example, is common ground for both Catholics and Christians, and yet you will never find a Bible that says "God is a Trinity".
So also will you never find an accurate translation of the Bible that says the word "Catholic". Or Pope. Or Purgatory. Or a number of other things Catholics believe in. Many Catholic doctrines, far from being absent in name, are absent in concept, too. Thus, if Sola Scriptura being absent in name is enough to discount it, so also is Catholicism utterly dead.
Furthermore, Sola Scriptura isn't even the only name you can give the doctrine. I personally like to call it the Sufficiency of Scripture, simply because this is easier to understand by the common man. If I wanted to be extremely petty, I could just call it "the doctrine that the scriptures make the man of God complete, thoroughly equipped for every good work", which is in the scriptures. Same doctrine, different name.
3. "Verse 15 clearly says it is only referring to the scriptures Timothy was familiar with from birth, i.e. the Old Testament".
I do have to commend the Catholics that try this argument. I wish reading more to discover the context was something all Catholics would practice, since this would obliterate Catholicism's rare attempts to defend their religion with scripture, and a deeper study of scripture would show Catholics that Catholicism is false. Alas, in this case, backing up one verse really doesn't help Catholicism.
First, let's read it: "and that from childhood you have known the Holy Scriptures, which are able to make you wise for salvation through faith which is in Christ Jesus." This already pokes holes in Catholicism, as it does not teach that salvation is through faith which is in Christ Jesus. In Catholicism, salvation is by "grace", which is handed out piecemeal through the 7 sacraments. In other words, they add works to faith, and even then salvation is never assured. It is the consistent testimony of scripture that salvation is by grace alone, through faith alone, not of works (Ephesians 2:8-9). Romans 11:6 even explicitly defines grace as being the exact opposite of works. Therefore, adding verse 15 only adds an extra layer of devastation to the Catholic Church.
Furthermore, all means all, and that's all all means. With that cliche out of the way, Paul does not say "this only refers to the Old Testament". Paul says all scripture. That includes the Old Testament, but is not limited to it. In fact, in 1 Timothy 5:18, Paul had already told Timothy that Luke's Gospel was scripture. In Paul's mind, there was literally no distinction between the Gospel of Luke and the law of Moses.
And this happens to be a common view between Catholics and Christians. We have no dispute over the inspiration of scripture. Except, apparently, when it comes to this particular argument against 2 Timothy 3:16-17.
So, of the three responses I've seen to 2 Timothy 3:16-17, one of them completely misses the point, and the other two are mutually destructive. Beyond that, Catholic responses to this verse dodge it completely, most often "who compiled your Bible?".
I very rarely use the word I am about to use, but I don't feel especially hesitant to say that 2 Timothy 3:16-17 is irrefutable proof that the Bible alone is the authoritative source of Christian doctrine and the infallible guide to faith. At the very least, given that Christians and Catholics both agree that the Bible is the inspired word of God, I think we should also be able to agree that anything that disagrees with the Bible is wrong. But Rome even teaches a completely different Gospel than the one found in the Bible, and so we don't even need to believe Sola Scriptura to say that the Catholic Church is utterly heretical, and that those who take it seriously are no safer than, for example, Mormons (Galatians 1:8).
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An attempted response from a Catholic
When this article was originally published as a post on the God Squad Apologetics Facebook page, a Catholic attempted to respond with the following:
"I want to start off by saying this isn’t coming from a place of hostility, just one of trying to clarify some things. I’m not going to be the one to try and refute this verse in any capacity, but I do think that a key part of the verse is ensuring the correct interpretation of scripture. The reason Catholics get so hung up on this notion of interpretation is because there are some extremely important key differences in scripture interpretation that lead to so many Protestant vs. Catholics debate. The Real Presence of Jesus in the Eucharist is a prime example.
So while I do agree that all scripture is profitable, divinely inspired, and necessary, the Church’s history dating all the way back to the time of Jesus’ ascension grants them the authority to determine what it meant and how we can apply it to our lives. I truly admire your zeal for apologetics and respect the wealth of knowledge you guys have, but I think there is a kinder way to discuss our differences."
As it is particularly rare for me to find a respectful Catholic, I have decided to give this one the honor of a direct response, published here on Bible Brain.
I want to acknowledge the first half of the comment, just to show I haven't ignored it, but I don't really have a direct response, as I am very familiar with the mentality behind the Catholic argumentation, and discussing the real presence would be off topic (though it has been addressed on this ministry before. Here, for example).
As for the second half, first, I want to highlight what the Catholic admitted to believing about the verse cited, but more importantly, what he didn't admit he believed. As I said in the article (see point one), I know Catholics agree with all of verse 16. They have to, it's part of their own tradition. But verse 17 is what's important. Verse 17 says that all of this makes the man of God complete (i.e. requiring nothing else), and thoroughly equipped (i.e. more than enough) for every (i.e. no exceptions) good work. That is something that no Catholic will ever be able to affirm.
The whole reason Catholics can't just acknowledge the Sufficiency of Scripture is because there are a range of things outside the Bible that the Catholic Church believes you must have in order to be complete, or good works for which the Bible does not equip us. This ranges from the minor (e.g. the perpetual virginity of Mary) to the major (e.g. a distinction between mortal and venial sins). You will find neither of the example concepts in the Bible, especially not since the Bible refutes both of these concepts. The really strange thing is that some of the minor concepts are turned major by the Catholic Church. Mary's virginity after Jesus' birth is irrelevant to me. Why would I want to discuss her sex life? That's between her, Joseph, and God. But according to the Catholic Church, because I do believe Mary and Joseph consummated their marriage after Jesus was born (Matthew 1:25), and that this produced half siblings for Jesus (Matthew 13:55-56) (who actually rejected Him, as the scriptures foretold (Psalm 69:8), and some of them converted, and two of them actually wrote scripture), I am therefore anathema. To take a minor issue like that and turn it into "believe us or go to Hell" requires straying from, and even contradicting the Bible. Therefore, it is impossible for a Catholic to honestly claim they believe verse 17.
The historicity of the Catholic Church is also a poor argument, for two reasons:
1. It's just not true. The Catholic Church cannot trace its origins back to the ascension of Christ. Aside from the fact it has evolved a lot since its origins, it takes huge stretches of the imagination to say the Catholic Church is historical. Indeed, the Bible itself is a historical document, written by the hands of the Apostles, no less. If the Catholic Church really did exist in the first century, and the Apostles really were Catholic, we would expect to see some semblance of Catholicism in the Bible. But we don't. Catholics always appeal to the second century or later. Even the majority of the quotes they use don't really say much about the Catholic Church (the word "catholic", by the way, actually originally meant "universal", meaning you can even find early references to the "catholic" Church, with a small C). On top of that, other quotes from the same, similar, or later sources show that even the so-called "Church Fathers" often disagree with the modern Catholic position.
2. Even if it was true that the Catholic Church could trace its origins back that far, that does not show that they have ultimate authority over the scriptures. It couldn't. It's a book, not a painting. A painting can contain meanings not readily apparent to the observer, but a book uses language, which is intended to convey a specific meaning to all audiences. You and I are speaking English right now. Imagine if my brother commented below and said "no, Brian is actually a Catholic. He doesn't believe Sola Scriptura". Would you believe him? Or would you read my posts, and my comments, and determine that my brother, who knows me a right sight better than you do, is nevertheless wrong about what I believe?
Let's put it another way: Did Paul have authority? The answer, according to both our religions, is yes. Now, Paul preached the Gospel to some Jews in Berea. These Jews "searched the scriptures daily to find out if these things were so".
For this, Luke says they were "fair minded". You can read this in Acts 17. Now, we both agree Paul was a good teacher. The Berean Jews had less authority than he did, didn't they? Paul saw Jesus, the Bereans only had the scriptures. If the Bereans could test Paul, why can't Christians, who have more scriptures than the Bereans did, test the Catholic Church, who have less authority than Paul?
There will never be a sensible argument that would allow the Catholic Church to authoritatively interpret scripture for everyone else. The Apostles submitted to the test of scripture. Anyone who resists the test of scripture is, therefore, not following an Apostolic Church.