We are considering the doctrine of Scripture affirmed by the Protestant Reformers, which is encapsulated in the Latin phrase sola Scriptura. According to the Reformation—and biblical—principle of sola Scriptura, Scripture is the only infallible rule of faith for the church. Because the Word of God is the only theopneustos—God-breathed—special revelation that we possess today (2 Tim. 3:16), then no rule of faith can supersede Scripture. There is no higher court to which we can appeal for faith and practice, for there is nowhere else besides Scripture where we can surely find God's voice today. That God's Word is inspired does not mean that He dictated it or that He overrode the personalities, gifts, and stylistic choices of the human authors through whom the written Word of God has come to us. It does mean that He worked in and through these authors such that their words are His words.
Sola Scriptura also leads us to the doctrine of biblical sufficiency. To say that Scripture is sufficient is to say that the Bible contains all that we need for determining what we must believe and how we are to live before God. Scripture must be interpreted if we are to understand what we are to believe and how we are to act, but the sufficiency of Scripture indicates that we need no other source of special revelation for faith and life in addition to the Bible.
Passages such as 2 Timothy 3:17 affirm the sufficiency of Scripture. Having affirmed that God's Word is profitable for "teaching, for reproof, for correction, and for training in righteousness" (v. 16), Paul explains that Scripture is enough to make us "complete, equipped for every good work." Scripture in its totality is all that is needed so that we will be completely prepared to serve the Lord. A good work is anything that is pleasing to God, so this text covers everything from determining sound doctrine to knowing the deeds the Lord requires of us as proof of our faith in Him (see James 2:14–26). Being equipped for every good work requires understanding the doctrinal foundations of God-pleasing actions and the actions themselves, as is seen in how the New Testament Epistles typically move from presenting doctrine that must be believed to practical application and moral instruction. John Calvin comments on today's passage that to be complete means to be "one in whom there is nothing defective." To avoid being defective with respect to faith and life, we must study Scripture and put its teachings into practice.
We are tempted to look for God's will in places other than the one place He has revealed it—His Word. As we ponder the will of God for our lives, we must be careful to follow the guidance of Scripture. It is sufficient to give us the principles we need to know to please God wherever we are and whatever we are called to do.