Robertson's Word Pictures:
The man of God (ο του θεου ανθρωπος). See 1Ti 6:11.
May be complete (ινα η αρτιος). Final clause with ινα and present subjunctive of ειμ. Αρτιος is old word (from root αρω, to fit), specially adapted, here only in N.T.
Furnished completely (εξηρτισμενος). Perfect passive participle of εξαρτιζω, rare verb, to furnish (fit) fully (perfective use of εξ), in N.T. only here and Ac 21:5. In Josephus. For καταρτιζω, see Lu 6:40; 2Co 13:11 .
"our saving faith derives its force, not from capricious reasonings, but from what may be proved out of the Bible" (Cyril of Jerusalem).
"Vincent of Le'rins (c. 450) took it as an axiom the Scriptural canon was 'sufficient, and more than sufficient, for all purposes'" (J. N. D. Kelly 43).
"'How then,' says one, 'shall we be able to renew it [i.e., the soul], thus fallen and relaxed, to strength? what doing, what saying?' By applying ourselves to the divine words of the prophets, of the Apostles, of the Gospels, and all the others; then we shall know that it is far better to feed on these than on impure food, for so we must term our unseasonable idle talking and assemblies" (HOMILY XVIII. JOHN 1:35-37).
John Trapp's Commentary: May be perfect] αρτιος ( omnibus numeris absotutus), with a perfection of parts, able and apt to make use of the Holy Scriptures to all the former purposes, for the behoof or benefit of his hearers. The authority of the Fathers, saith a grave and learned divine, I never urge for necessity of proof (the Scripture is thereto all-sufficient and superabundant), but only either in some singular points to show consent; or, 2. In our controversies against anti-christians, anti-nomists, Neopelagians; or, 3. When some honest passage of sanctification or seasonable opposition to the corruption of the times is falsely charged with novelty, singularity, and too much preciseness. (Mr Bolton’s Four Last Things.)
For a time, oral teaching served a vital purpose in the Christian ecclesia. But in order to preserve the Gospel and facilitate its spread, the ecclesia committed its beliefs to writing (Cf. 2 Pet. 3:1, 2). Interestingly, Lucius Lactantius also contended that Holy Writ did not grow out of the Christian religion, but the Christian religion out of Holy Writ (Divine Institutes 4.4.5). Yes, Christians are supposed to be "people of the book." Jehovah God always purposed that the teachings of Christ would be committed to writing, and these writings as Vincent said, are sufficient "and more than sufficient" for all Christian purposes, even though Vincent thought tradition was vital to avoid misinterpreting Scripture. I'm not sure he would insists that tradition precedes the Bible though.