Those who wish to oppose the doctrine of Sola Scriptura typically run to 2 Thessalonians 2:15 as one of the first passages to discuss. As will be demonstrated below, this verse does not support such abuse, and - in fact - demonstrates the eisegetical mindset of those who seek to use it to oppose a doctrine that our only infallible rule of faith is Scripture.
2 Thessalonians 2:15 Therefore, brethren, stand fast, and hold the traditions which ye have been taught, whether by word, or our epistle.
The usual way this verse is abused is to make a loose claim, such as:
a) See, tradition according to Scripture includes both written and oral components; and
b) See, oral tradition is also as binding as written tradition.
There are several reasons why these are abuses, and there are several reasons why even these abuses are not particularly helpful to those who usually attempt them.
Reasons why such loose statements are abuses of the text or unhelpful to those trying to use them.
1(a). We do not know precisely the content of the traditions mentioned is. The significance of this fact will become apparent shortly.
1(b). We know from the context that the general content of these traditions is the gospel:
13But we are bound to give thanks alway to God for you, brethren beloved of the Lord, because God hath from the beginning chosen you to salvation through sanctification of the Spirit and belief of the truth: 14Whereunto he called you by our gospel, to the obtaining of the glory of our Lord Jesus Christ. 15Therefore, brethren, stand fast, and hold the traditions which ye have been taught, whether by word, or our epistle.
2. The "brethren" (not simply the bishops/elders) are those who received the "traditions" mentioned.
3. The "traditions" mentioned are a combination of the things preached to those brethren and "our epistle" and not between the things preached and Scripture generally.
Impacts of the facts above.
Why are these three/four facts significant to stop abuse of the verse?
A) The verse is not saying to hold anything taught outside of Scripture, as such.
B) The verse is not saying to hold fast to something other than the gospel.
C) The verse is not saying making a general statement about all teachings by every apostle.
D) The verse is not saying that Scripture generally fails to contain the gospel to which Paul required the Thessalonians to hold fast.
Specific Abuse 1
If someone is trying to say that we need to permit some "tradition," because this verse says so, we need to ask ourselves (and them, if they'll answer) three questions:
1) Is the tradition that they want us to permit the gospel preached by Paul to the Thessalonians, or something else?
2) Is the tradition they want us to permit something that they can demonstrate Paul taught to the Thessalonians at all?
3) Is the tradition they want us to permit something that they can demonstrate that any of the apostles or prophets of the apostolic age taught to the Thessalonians?
If the answers are "something else," "no," and "no" (as is usally the case) then it should be apparent that their reliance on this verse is completely in appropriate.
Specific Abuse 2
Likewise, if someone is trying to use this verse to suggest that we must consider as infallibly authoritative something in addition to Scripture, we need to ask ourselves (and them, if possible) three questions:
1) Does the verse contrast Scripture and oral traditions or "our epistle" and other "things preached"?
2) Does the verse say that the Thessalonians had been preached extrascriptural doctrines?
3) Does the verse explain anything about the "things preached" beyond that they were the "truth" and "the gospel"?
If the answers are "the latter," "no," and "no" then it should be apparent that the verse cannot stand for the proposition for which they are attempting to use it.
Specific Abuse 3
Finally, if the verse is provided as an argument that the magesterium of the church has been entrusted with oral teachings that are passed down orally for long periods of time, but which must be accepted when finally revealed to the public, we must ask the following questions:
1) Is there any reason to think that Paul taught things in secret, especially from this verse?
2) Is the verse directed to the leaders of the Thessalonian church or to the brethren?
3) Does the verse specify that the "things taught" were not things that were committed to writing?
If the answer is "no," "brethren," and "no," then it should be apparent that the verse is being abused by the person citing it.
As demonstrated above, 2 Thessalonians 2:15 does not defeat Sola Scriptura, nor does it establish the "traditionist" positions. It's important, of course, to recall that those two things are separate issues. The "traditionist" position that we have to have an infallible magesterium in addition to Scripture is not proved simply by attacking Sola Scriptura. For example, the "traditionist" claims for their tradition are not simply that there is a body of inspired knowledge that is additional to Scripture that was taught by the apostles. Instead, the claim is usually a claim to be able to - in essence - add to the base of inspired knowledge additional infallible teaching that was not the teaching (by word or letter) of Paul to the Thessalonians. In short, to make assertions that 2 Thessalonians 2:15, because it uses the words "traditions" is supportive of a "traditionist" position such as Roman Catholicism or Eastern Orthodoxy, is simply to demonstrate one's unfamiliarity with the text, and one's inability to consider what the text itself has to say.
May God give us wisdom to hold fast to the gospel that Paul preached to the Thessalonians,