What does 2 Timothy 3:16-17 mean?

16 All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness: 17 That the man of God may be perfect, throughly furnished unto all good works. (2 Timothy 3:16-17 KJV)

William Burkitt New Testament

Our apostle closes this chapter with an exhortation to Timothy to persevere in his study of the holy scriptues, by an argument drawn,  

1. From the dignity and authority of the scriptures; 2. From their utility; 3. From their perfection.  

1. From their dignity and authority, They are given by the inspiration of God: that is, they are not the contrivance of any man’s wit and fancy, but a revelation of the mind and will of God; and those that wrote them were excited to it, and assisted in it, by the Spirit of God; no part of scripture had either angels or men for its author, but every part of scripture is divinely inspired or breathed by God, both for matter and order, style and words.  

A second argument is drawn from the utility and sufficiency of the holy scriptures; they are profitable for doctrine and instruction, teaching us what to know and believe in order to salvation, concerning God, and Christ, and ourselves, &c. for reproof of error, and confutation of false doctrines, for correction of sin and evil manners, for instruction in righteousness, directing us how to lead a holy and righteous life, according to the will of God.  

A third argument is taken from the perfection of them; they are able to make the man of God perfect, thoroughly furnished unto all good works; that is, to make the ministers of Christ complete in knowledge, faith, and holiness, every way fitted for their work and duty, as Christians, and as ministers.  

Observe here, 1. That the scriptures of the Old Testament, and not of the New, must be the scriptures here intended, they being the only scriptures which Timothy had known from a child; that was before the scriptures of the new Testament were written.  

Observe, 2. That the apostle doth not say that these scriptures were of themselves sufficient to make Timothy wise unto salvation, but only that with faith in Christ Jesus they were sufficient for that end; much more then must the scriptures both of the Old and New Testament together, when accompanied with faith in Jesus Christ, be sufficent for that end.  

Observe, 3. That the scriptures are a perfect, plain, and sufficient rule, in all things necessary to salvation.  

1. They are a perfect rule; because the writers of them were inspired, and consequently their writings are infallible.  

2. They are a plain rule; otherwise they would be no rule at all, of no more use to direct our faith and practice than a sun-dial in a dark room is to tell us the hour of the day. A rule that is not plain, whatever it may be in itself, is of no use to us till it is made plain.  

3. They are a sufficient rule; they are able to make the man of God perfect, and wise to salvation. Here the church of Rome distinguishes, and says, the scriptures are sufficient to salvation, but not to instruction, to whom one of the martyrs replied, “If so, God send me the salvation and you the instruction.”  

It is conceived by some that this was the last epistle that ever St. Paul wrote; if so, this is the last charge that ever he gave, and concerns us the more to attend to the solemnity of it. The chapter before us is St. Paul’s Cygnea Cantio, his last and sweetest song; by a spiritual sagacity he saw his end approaching, and the time of his martyrdom to be at hand; he therefore, like a dying man, adjures TImothy in a most awful and tremendous manner, to preach the word with all diligence and care, which he had so highly extolled in the foregoing chapter, as being able to make all persons wise unto salvation.