John Calvin Commentary 2 Timothy 3:17

"That the man of God may be complete, furnished completely unto every good work." — 2 Timothy 3:17 (ASV)

That the man of God may be perfect. Perfect means here a blameless person, one in whom there is nothing defective; for he asserts absolutely that Scripture is sufficient for perfection. Accordingly, whoever is not satisfied with Scripture desires to be wiser than is either proper or desirable.

But here an objection arises. Since Paul speaks of the Scriptures, which is the name given to the Old Testament, how does he say that it makes a man thoroughly perfect? For, if this is so, what was afterwards added by the apostles may be thought superfluous. I reply, regarding the substance, nothing has been added; for the writings of the apostles contain nothing other than a simple and natural explanation of the Law and the Prophets, together with a manifestation of the things expressed in them. This praise, therefore, is not inappropriately bestowed on the Scriptures by Paul; and, since its instruction is now made more complete and clear by the addition of the Gospel, what can be said but that we should certainly hope that the usefulness, of which Paul speaks, will be much more evident, if we are willing to put it to the test and receive it?