What does 2 Timothy 3:16 mean?
After noting the importance of the "sacred writings" for wisdom for salvation in the previous verse, Paul makes one of the most important and frequently-quoted statements in the entire Bible: "All Scripture is breathed out by God." The "All Scripture" in this case most specifically referred to the Old Testament, since the full New Testament did not yet exist. At the time Paul wrote these words, books such as the Gospel of John and Revelation had not yet been written. However, this principle would still apply to all Scripture given by God, including the 27 books of the New Testament. New Testament writers recognized Scripture even as it was written (2 Peter 3:15–16).The description here of God's word is the Greek theopneustos. This is very literally translated as "God-breathed." Human authors put the words to paper, through their own personal perspectives and styles. But the ultimate source of this information is not human, but divine. The Greek language makes this particular description even more layered. The Greek root word pneo is used for wind, breath, a spirit, or "the" Spirit. This is a wordplay Jesus uses when speaking to Nicodemus (John 3:8). In a symbolic sense, in Greek, the word Paul uses is a model of the Bible itself: an extension of God's will, formed out of His spirit, in written form.
As such, this written Scripture is perfect (Psalm 19; 119). Because all Scripture is perfect, it is "profitable" for many areas of life. Paul lists four areas in this verse. First, Scripture is profitable for teaching. It is to be used to instruct people to know God better. Second, Scripture is profitable for reproof or rebuke, the idea of exposing or pointing out sin. Third, Scripture is useful for correction. Scripture both points out sin and offers a solution to it. Fourth, Scripture is profitable for training in righteousness. Though similar to teaching, training is more focused on practical application. From Scripture we learn what is true, what is wrong, how to correct wrong, and how to apply truth.