Second Thessalonians 2:15:
“So then, brethren, stand firm and hold to the traditions which you were taught, whether by word of mouth or by letter from us.” This is perhaps the favorite verse of Catholic apologists when they want to support the Catholic appeal to tradition, because the verse plainly delineates between the written word and oral “traditions.”
The Greek word is paradosis. Clearly, the apostle is speaking of doctrine, and it is not to be disputed that the doctrine he has in mind is authoritative, inspired truth.
So what is this inspired tradition that they received “by word of mouth”? Doesn’t this verse rather clearly support the Catholic position?
No, it does not. Again, the context is essential to a clear understanding of what Paul was saying. The Thessalonians had evidently been misled by a forged letter, supposedly from the apostle Paul, telling them that the day of the Lord had already come (2 Thess. 2:2). The entire church had apparently been upset by this, and the apostle Paul was eager to encourage them.
For one thing, he wanted to warn them not to be taken in by phony "inspired truth."And so he told them clearly how to recognize a genuine epistle from him: it would be signed in his own handwriting: “I, Paul, write this greeting with my own hand, and this is a distinguishing mark in every letter; this is the way I write” (3:17). He wanted to ensure that they would not be fooled again by forged epistles.
But even more important, he wanted them to stand fast in the teaching they had already received from him. He had already told them, for example, that the day of the Lord would be preceded by a falling away, and the unveiling of the man of lawlessness.“Do you not remember that while I was still with you, I was telling you these things?” (2:5). There was no excuse for them to be troubled by a phony letter, for they had heard the actual truth from his own mouth already.
Nothing in Scripture suggests that the tradition Paul and the other apostles delivered is infallibly preserved for us anywhere except in Scripture itself. Now, no one–even the most impassioned champion of sola Scriptura–would deny that Paul had taught the Thessalonians many things by word of mouth. No one would deny that the teaching of an apostle carried absolute authority. The point of debate between Catholics and Protestants is whether that teaching was infallibly preserved by word of mouth. So the mere reference to truth received firsthand from Paul himself is again, irrelevant as support for the Catholic position. Certainly nothing here suggests that the tradition Paul delivered to the Thessalonians is infallibly preserved for us anywhere except in Scripture itself.
In fact, the real thrust of what Paul is writing here is antithetical to the spirit of Roman Catholic tradition. Paul is not encouraging the Thessalonians to receive some tradition that had been delivered to them via second- or third-hand reports. On the contrary, he was ordering them to receive as infallible truth only what they had heard directly from his own lips.
Paul was very concerned to correct the Thessalonians’ tendency to be led astray by false epistles and spurious tradition. From the very beginning the Thessalonians had not responded to the gospel message as nobly as the Bereans, who “received the word with great eagerness, examining the Scriptures daily, to see whether these things were so” (Acts 17:11).