Like all reformation Christians, you are trying to build a comprehensive legal case from document not suited to such application. That exercise requires certain inferences that while useful to the prosecution, are not comprehensively demonstrable from the source documentation.
I am not a reformation Christian...I am a Christian...a follower of Christ. I believe He died on the cross for all of my sins and has separated them as far as the east is from the west.
Case in point: 2 Tim 3:16 tells us a man of God can not be complete without Scriptures. It does NOT tell us the man of God is complete BY Scriptures.
The verse you cite does tells we are made complete by the Scriptures.
The verse you cite comes at the end of 2 Timothy 3 in which many warnings are given by Paul about apostasy, false teaching, etc.
Indeed in v 15 it tells us "and that from childhood you have known the sacred writings which are able to give you the wisdom that leads to salvation through faith which is in Christ." I note Paul doesn't refer to anything other than the sacred writings which have to be the Old Testament at this point in time.
v16 then clarifies that all Scripture is inspired by God... v17 notes that with the Scriptures the man of God may be adequate, equipped for every good work.
the greek word for adequate/complete, depending on English translation, in verse 17 is ἄρτιος and means perfect, complete, ready, fitted.
So right here in the very passage you are sighting we do have a clear teaching that the Scripture (Bible) is able to teach us everything we need to know about teaching, reproof, correction, and training in righteousness.
We have Paul telling us in v15 about the sacred writings learned from childhood.
With the inspired Word of God why would you need any man made teachings?
A somewhat subtle point, but it is the crux of the argument between Reformed and Catholics over the authority of Scripture.
If Scripture isn't supreme, especially based on the verse we've been discussing in 2 Timothy, then what is? and why?
In effect, the dilemma you pose gets no traction with Catholics because it assumes a reformation orientation regarding the authority of Church documents.
A rough explanation, I know. And probably not without faults.
Perhaps the analogy of a King James Cultist would work better.
Said cultists have elevated their preference for a particular translation of the Bible to such an extent they perceive a Satanic plot in all other translations. So much so, discrepancies between the King James and all other translations are regarded as prima facie evidence of said plot. (I have even witnessed serious men trying to make the case the Sanhedrin were so incensed by the testimony of Stephen they physically assaulted him by biting)
You see Scripture as a contract, and use inference from other Scripture to fill in the legal holes. Catholics see Scripture as a Constitution with holes filled in by adjudication by the Church.
I guess part of the disagreement is that I don't see any legal holes the Bible has to fill. We have all we need to know about how to come to know Christ in the Bible. It teaches us how to pray. It teaches us how to have forgiveness. It teaches us every aspect of being a Christian we need to know as noted in 2 Timothy 3:16-17.
It seems you are saying the Bible is insufficient...which would contradict 2 Timothy 3:16-17.
Thus, to a Catholic, there is no inherent contradiction between the irrefutably plain statement of our Lord about Peter in Matthew 16:18, and a more metaphoric understanding in the Catechism.
So which is it then regarding Peter? I don't understand how it can be both as you are claiming. The catechism, which as I understand it, is the official position of the Catholic Church. And it clearly says, and correctly I might add, that Christ is building His church on Peter's confession....not Peter. This understanding about Peter's confession is supported as we read the passage in its context.
I am not a reformation Christian...I am a Christian...
Are you not of the "brand" of Christian that takes the Scripture to be the ONLY authoritative rule of faith and practice? If so, then you are a reformation Christian by definition, and quibbling about it will do nothing but derail a potentially edifying dialog.
Nope. Sorry. You are positing the fitting of an essential piece of the puzzle, without which said puzzle can not be complete, is ALL that is needed to complete the puzzle. A that is not a logically supportable proposition, and no amount of fixating on the proper definition of "complete" is going to affect that dynamic.
Are not your inferences, indeed ANY teaching, that is not explicitly commanded in Scripture, man made? If not, why are yours inspired but mine are not?
The Church.
and why?
Because Scripture does not tell you what is a proper hermeneutic and what is not.
What would you say to a student who saw no need for Algebra?
You are correct. I am saying the Bible alone is insufficient. And that doesn't contradict 2Tim3 for the previously stated reasons.
That the Bible alone is insufficient is further demonstrated by the fact that it gives precious little insight into sin in all it's forms and guises.
Trying to use the Bible as a legal code is to fall into the same error as the Jews of Jesus' day.