To begin with, I need to define the position I will be defending here. One negative, one positive.
What Sola Scriptura is not -
Sola Scriptura is not a claim that all truth is found in the Bible.
Sola Scriptura is not a claim that for all time God has spoken only through the Bible.
Sola Scriptura is not a claim that every verse is equally clear to every person.
Sola Scriptura is not a claim that the Church has no place in interpreting the Bible.
Sola Scriptura is not a denial of all traditions.
Now, the doctrine of Sola Scriptura is not any of these, what is it?
Sola Scriptura states that the Scriptures alone are sufficient to function as the infallible rule of faith for the Church.
Sola Scriptura states that all that one must believe to be a Christian is found in Scripture, and not in another source.
Sola Scriptura states that all that is not found in Scripture (by good and necessary consequence) is not binding upon a Christian.
Sola Scripture states that all tradition is checked by and subject to Scripture. (points from RCC)
Sola Scriptura is simply this, that "all things necessary for salvation and concerning faith and life are taught in the Bible clearly enough for the ordinary believer to find it in there and understand." (SS p.3)
Ok, so having defined the position I'm trying to defend, let me launch into 2 Timothy 3 to defend the sufficiency of Scripture.
To set the context. Paul is writing to Timothy during what seems to be the last years of his life. In contrast to the book of Philippians where he seems to have an assurance that he will be released to do more ministry (Philippians 1:25), he is evidently preparing for death (2 Timothy 4:6-8). Within the letter, Paul repeatedly warns Timothy of the times to come, and to prepare for them. Chapter three is one of such occasion.
I'm going to quote the whole chapter and focus on the last few verses.
2 Timothy 3 (ESV translation)
1But understand this, that in the last days there will come times of difficulty. 2For people will be lovers of self, lovers of money, proud, arrogant, abusive, disobedient to their parents, ungrateful, unholy, 3heartless, unappeasable, slanderous, without self-control, brutal, not loving good, 4treacherous, reckless, swollen with conceit, lovers of pleasure rather than lovers of God, 5having the appearance of godliness, but denying its power. Avoid such people. 6For among them are those who creep into households and capture weak women, burdened with sins and led astray by various passions, 7always learning and never able to arrive at a knowledge of the truth. 8Just as Jannes and Jambres opposed Moses, so these men also oppose the truth, men corrupted in mind and disqualified regarding the faith. 9But they will not get very far, for their folly will be plain to all, as was that of those two men.v.1-9 emphasize exactly the opposition that Timothy will be facing. There will be times of difficulty because people will be depraved (I note that "disobedient to parents" is located in a list of pretty serious sins, makes you (me!) think). Timothy is encouraged to avoid such people (v.5) for they have nothing.
10You, however, have followed my teaching, my conduct, my aim in life, my faith, my patience, my love, my steadfastness, 11my persecutions and sufferings that happened to me at Antioch, at Iconium, and at Lystra--which persecutions I endured; yet from them all the Lord rescued me. 12Indeed, all who desire to live a godly life in Christ Jesus will be persecuted, 13while evil people and impostors will go on from bad to worse, deceiving and being deceived.In contrast to these people Paul encourages Timothy, reminding him of all that Paul has taught him and all that Paul has endured at the hands of such men. He warns Timothy that the life that he's encouraging Timothy to live will entail persecution at the hands of evil men.
14But as for you, continue in what you have learned and have firmly believed, knowing from whom[a] you learned itThe word "but" begins verse 14, signifying a contrast from the previous verse. In contrast to the evil people and impostors in verse 13 who go from bad to worse deceiving and being deceived, Timothy is encouraged to continue in what he has learned and has firmly believed. Their deceiving and being deceived is set up against Timothy continuing in what he has learned and firmly believed. Paul then makes a point to note that Timothy is to do this knowing "from whom(plural) [he] learned it", reminding Timothy of how this teaching has borne fruit in the lives of his mother and grandmother (2 Timothy 1:5).
Paul then proceeds remind Timothy exactly what was taught to him.
15and how from childhood you have been acquainted with the sacred writings, which are able to make you wise for salvation through faith in Christ Jesus.Now, Timothy had followed Paul for so many years through so many trials. He had direct access to a source of great theology and knowledge. If there were traditions that were needed to help Timothy stop from being like the deceivers, Paul would have reminded Timothy of them. But Paul doesn't say "remember those traditions I taught you," (I will deal with the "traditions" passages in a separate post) but he instead reminds Timothy of the source of his faith, the sacred writings. They are "able to make you wise for salvation through faith in Christ Jesus."
16All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness, 17that the man of God[b] may be competent, equipped for every good work.Paul then proceeds to explain why these sacred writings are thus able. They are not written by mere men, but rather "breathed out by God." When Scripture speaks, it's God speaking. The Scriptures thus carry with it God's very own authority. Because they are not written by men, but by God, they carry with it God's authority, and God's power. They are thus supernatural and profitable for teaching, reproof, correction, and training in righteousness. All these things lead Paul to conclude that Scripture allows for the man of God to be "competent, equipped for every good work."
The word translated "competent" is ἄρτιος. What does that mean? Thayer's Lexicon says it means "fitted; complete, perfect," my Greek NT dictionary (UBS 4th edition) says, "fully qualified," Vincent's Word Studies (acessed via e-Sword) says "complete; but the idea is rather that of mutual, symmetrical adjustment of all that goes to make the man: harmonious combination of different qualities and powers."
Related to that word is the word translated "equipped" ἐξηρτισμένος which is the passive perfect participle of ἐξαρτίζω (notice the resemblance to the above word?). Thayer's has "to complete, finish - to furnish perfectly, to finish, accomplish," Greek NT dictionary - "to equip," Vincent's Word Studies - "fills out the idea artios; fitted out."
It's clear that these words are broad in scope. Scriptures come with the authority of God behind it, they are not only useful, but furnish completely, fills out, makes fully qualified. What does this mean? It means that the Scriptures are sufficient for every good work. Indeed, the NIV translates this (which in essence is another definition) as "so that the man of God may be thoroughly equipped for every good work."
Now, the objection is that if this verse proves sufficiency, it proves too much, for Paul is speaking only of the Old Testament here. In response, i would point out that through Paul is referring to the Old Testament in his initial statement, he broadens his answer to include all that is Scripture. Paul has already quoted Luke as Scripture earlier, and clearly knows that he himself is inspired by God (as I argue here). Vincent Cheung comes to the same conclusion after examining how Paul refers to Scripture elsewhere and the Bible's view on authority in his article "Sufficient and Profitable" (the link is to the relevant excerpt, the entire article is in his book The Ministry of the Word) He concludes with saying,
"Since the New Testament documents are regarded as inspired and even called "Scripture," we may with complete certainty regard them as "God-breathed." Both the Old Testament and the New Testament are "Scripture," and they make up one book that is our Bible. Therefore, there is no problem in regarding the verse as asserting, "The whole Bible is God-breathed." In fact, there is no excuse in thinking otherwise."Finally, though I feel like I've already addressed this by making a positive presentation, one objection has been brought forth that Paul is speaking to Timothy ceteris paribus argument for "Tradition," where it is claimed that Paul is speaking to Timothy with the knowledge that Timothy already knows tradition so now Scripture is able to make him complete.
My objector wrote, "If a man just has Tradition, he isn't complete. But then the Bible comes along, and suddenly he has been made complete; the Bible made him so. Thus, it is a true statement that the Bible is able to make a man complete. Whether or not the Bible is sufficient depends on the unspoken assumptions as to what the man in need of being completed already has."
In response to this objection there are two remarks -
1) This certainly cannot be established by the text, it may indeed be true (and I have to deal with the "traditions" passages in a future post), but it's certainly not sustainable here. There is no indication of "now the Scripture is able to..." being implied at all. So the objection raises up a possibility without establishing it.
2) In a positive presentation against this possibility, I would say that the context prevents us from understanding Paul to be speaking that way. Paul is talking specifically about not being like these evil men. Paul reminds Timothy of what he's had since birth, the sacred writings. If indeed Paul was talking of (extra-Scriptural) traditions that he's been taught as well, it makes no sense not to remind Timothy of them as well, as he is exhorting Timothy to not be like these evil men. Instead of pointing to both Scripture and (extra-Scriptural) tradition, Paul points to Scripture as the sole source of all things needed to make Timothy perfect, fully equipped for every good work.
So Scripture is sufficient for every good work. If something is not spoken of, it's not necessary.