"All scripture is inspired by God and profitable for teaching, for reproof, for correction, and for training in righteousness, that the man of God may be complete, equipped for every good work."
(2 Timothy 3:16-17)
These are wonderful verses on the importance of the bible, and how it is God-breathed." They say that Scripture is "profitable" for various good things (teaching, correction, reproof, training in righteousness), so that we can be "complete." But to say the Bible is profitable for these good things is not to say that nothing else is profitable for them. Prayer, for example, is profitable, too. Nor would it be meaningful even to say that the Bible is "more" profitable than prayer, since the Bible is, of course, of no use to the person who does not build a relationship with God through prayer. Thus, it would be odd to take the "profitability" of Scripture and interpet it as meaning that the Bible alone is necessary.
Purely at the level of logical argument, moreover, for the Christian who thinks these verses might point to sola scriptura, notice that there are stronger verses than these in the NT, which say other things fully make us perfect and complete and are not merely profitable for doing so. In James 1:4, "steadfastness," and the "work" steadfastness does, is said simply to make us "perfect and complete, lacking nothing." Obviously James wouldn't want us to press this idea so far we base our entire Christian theology on steadfastness alone. Nor could Paul be asking us to do this with the Scriptures in 2 Timothy 3:16-17.
Even in 2 Timothy itself, only a few verses before 3:16-17 (that is, in 2 Tim 2:21), we find that purging oneself from "what is ignoble" will make a person "a vessel for noble use, consecrated and useful to the master [God]", and "prepared to every good work." Paul is extolling a particular kind of virtue here (watching what company you keep), and yet the virtue is said to prepare us for every good work, like the scriptures do in 2 Timothy 3:16-17. Just sticking with 2 Timothy, we also have Paul using Tradition as authoritative just a few verses before the ones under discussion (that is, Paul uses oral Tradition in 2 Timothy 3:8), where the names Jannes and Jambres (from the story of Moses) are drawn from Tradition alongside the Scriptures, and are never referred to in the OT account of this scene (Exodus 7:8ff). Finally, Paul tells Timothy to hold fast to what he has heard from Paul and pass it down, right there in 2 Timothy, and to tell others to do likewise (2 Timothy 2:2), and thus teaches oral Tradition. In summary, virtually the only verse that our Protestant brothers and sisters have tried to say proves sola scriptura (2 Timothy 3:16-17), fails to do, and is completely surrounded by verses that teach Tradition.
(Written by Christopher M. Butler)