Paul wanted to reemphasize the importance of Scripture in Timothy"s present and future ministry. His emphasis in 2 Timothy 3:15 was on its importance in Timothy"s life in the past. [source][source][source]
There is no reason to limit the universal force of "all" to matters of salvation. When the Greek word translated "all" or "every" (pas) occurs with a technical noun such as "Scripture," it is better to render it "all" rather than "every." [1] Furthermore, the context seems to suggest that Paul had Scripture as a whole in view. [2] Paul had been speaking of the Old Testament as a whole in 2 Timothy 3:15, and he undoubtedly carried that thought over into 2 Timothy 3:16. All Scripture is divinely inspired (Gr. theopneustos, lit. God-breathed, cf. 2 Peter 1:21). This fact in itself should be adequate reason for proclaiming it. It does not merely contain the Word of God or become the Word of God under certain conditions. It is God"s Word, the expression of His person (heart, mind, will, etc.). This was the view of the Hebrew Bible that Jews in the first century commonly held. [3] "Scripture" means sacred writing and applies to all divinely inspired writings (Old and New Testaments). The Greeks used the word graphe, translated "Scripture," to refer to any piece of writing, but the New Testament writers used it only of holy Scripture. When Paul made this statement the books of our Old Testament were the inspired writings he had in view primarily. However even in Paul"s day Christians recognized some New Testament books as inspired (cf. 2 Peter 3:16). [source][source][source]
"God"s activity of "breathing" and the human activity of writing are in some sense complementary (cf. 2 Peter 1:21)." [4][source]
Scripture is useful. Therefore Timothy should use it in his ministry. It is profitable for teaching (causing others to understand God"s truth) and reproof (bringing conviction of error when there has been deviation from God"s truth). It is helpful for correction (bringing restoration to the truth when there has been error) and training in righteousness (child-training type guidance in the ways of right living that God"s truth reveals). This is a selective rather than an exhaustive list of the ways in which the Scriptures are useful. [source][source][source]
"They are profitable for doctrine (what is right), for reproof (what is not right), for correction (how to get right), and for instruction in righteousness (how to stay right)." [5][source]
Consequently the man (or woman) of God has all that is essential to fulfill his (or her) ministry (cf. 2 Peter 1:3). The "man of God" refers to Timothy ( 1 Timothy 6:11) but also anyone who commits himself (or herself) to God, especially, in view of the context, those in positions of spiritual oversight. He is adequate (complete, filled out, equipped with all the essential tools he needs). [source][source][source]
"The Christian minister has in his hands a God-given instrument designed to equip him completely for his work." [6][source]
"Every good work" is the ultimate goal of our lives ( Ephesians 2:10). The mastery and use of Scripture is only a means to an end, not an end in itself. God did not give us the Bible to satisfy our curiosity alone but to enable us to help other people spiritually. [source][source][source]
"The divine inspiration of the Scriptures is stated in the Pastorals more forcefully than anywhere else in the NT." [7][source]