The Sufficiency of Scripture
Living most of my life in and around Houston, Texas, I have often wondered how mosquitoes can glorify God. The oppressive heat and humidity of Houston summers make the season bad enough, but the presence of these annoying bugs make it even worse. I joke sometimes that God created mosquitoes so that people can make an honest living selling mosquito repellent. But the truth is that I do not know how they glorify Him because the reason is not revealed to me in Scripture.
It can be tempting at times to go beyond what scripture says and speculate about things that God purposely does not reveal or to find answers to things that God does not want us to understand. We can use these speculations to blame God for things we do not understand or to excuse our lack of faith. These actions are much more dangerous than wondering about the purpose of mosquitoes.
To address this tendency to look beyond the Bible for truths about God and our salvation, theologians throughout the history of Christianity have held to the doctrine of the sufficiency of scripture. This doctrine helps to guard us from going beyond God’s perfect revelation and to trust Him for things we cannot know or understand.
Definition and Historical Development
What is the doctrine of the sufficiency of Scripture? The definition given in the Westminster Confession of Faith is very helpful. It says, “The whole counsel of God concerning all things necessary for His own glory, man’s salvation, faith, and life is either expressly set down in Scripture or by good and necessary consequence may be deduced from Scripture.” 
In other words, everything God wants us to know about Him and all He requires of us to know about salvation and life is found in the Bible. Theologians throughout the centuries such as William Tyndale, B.B. Warfield, John Calvin, Martin Lloyd-Jones, and John MacArthur just to name a few have defended the sufficiency of scripture.
For example, John Calvin wrote about the sufficiency of Scripture frequently in his commentaries and Bible introductions. He warned that we should not seek to go past what the Bible reveals to us and instead stay safe within the limits of what God has revealed to us. Calvin says,
“Once we grasp the idea that God’s word is the only path which allows us to investigate all that we may lawfully know about him and is likewise the only light by which we behold all that may be lawfully seen of him, it will easily stop us from acting impulsively. For then we will realize that by going beyond the bounds of Scripture we will be straying off into darkness, and will inevitably with every step wander, stumble, and trip up.” 
Modern theologian Michael Horton summarizes the typical Reformed understanding of the Bible saying, “although the Spirit is the judge of our faith and practice, he exercises this judgement through his word, never apart from it. The Father speaks to the Son through the perfecting agency of the Spirit.” 
The result of affirming the sufficiency of Scripture is not just a technical or scholarly activity. Affirming this doctrine helps us to rest in what God has revealed. Sinclair Ferguson speaks to this aspect of the doctrine by saying, “God has provided a safe and secure pathway for us in the directives, promises, examples, and commands of his written word. In their light we seek to interpret the significance of all his providences—including our mental processes and perceptions.” 
Is It Biblical?
To read about the sufficiency of Scripture from respected and trusted theologians is good and helpful, but what does the Bible say about its sufficiency? Does this doctrine line up with the Bible itself? We will look at a few passages in the Bible that supports its sufficiency for our lives.
In the Old Testament, Moses spoke about the sufficiency of Scripture when he wrote, “The secret things belong to the LORD our God, but the things that are revealed belong to us and to our children forever, that we may do all the words of this law” (Deuteronomy 29:29). In this verse we see that it is not for us to seek to discover God’s hidden will or secret knowledge; He does not reveal it to us because that knowledge belongs to Him, not us. All God wants to reveal to us is given to us perfectly in His word.
The sufficiency of Scripture is also found in the New Testament. In the Gospel of John, the entire purpose of the Gospel is given by John himself: “Now Jesus did many other signs in the presence of the disciples, which are not written in this book, but these are written so that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name” (John 20:30-31). Here John says that all anyone needs to know about having saving faith in Jesus can be found in His Gospel. It does not mean that the rest of the Bible is unimportant, but it shows that we do not need to look beyond the Bible to discover how to receive eternal life.
Jesus spoke to the sufficiency of Scripture when He told the parable of the rich man and Lazarus in Luke 16:19-31. After the rich man died and saw Lazarus in heaven, he pleaded with Abraham for his family, asking Abraham to send Lazarus from the dead to tell the rich man’s family the truth.
Abraham responded to the rich man by saying, “They have Moses and the Prophets; let them hear them” (Luke 16:29). In the days of the New Testament, saying “Moses and the Prophets” was the same as saying “the Scriptures” or “the Bible”. Moses represented the law, and the prophets represented the rest of God’s revealed word, so they represented the Jewish Bible or Old Testament at that time. Abraham told the rich man that Moses and the Prophets spoke sufficiently about what was required for salvation.
For the rich man to ask this of Abraham was a rejection of the Bible’s sufficiency. John Murray in the 1950s taught:
“[The rich man’s] repeated insistence that a voice from the dead would be effective in the case of his brethren clothed the persistent perversity of his thought, because he is insinuating that that is the way whereby men can come to repentance, that that is the way whereby men may escape the place of torment. And, therefore, he has set himself in direct contradiction to the wisdom and grace and goodness of God.” 
Paul confirms this doctrine as well by telling his fellow partner in ministry Timothy, “All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness that the man of God may be complete and equipped for every good work.” When Paul says “complete”, that speaks to the sufficiency as does “every good work”. This does not necessarily mean that a person cannot look to other sources beyond the Bible to grow, but it does mean the Bible is sufficient in showing all that a person needs to know to be properly equipped for all good works.
Let us continue to study the Bible and trust God that it reveals fully His glory, the truth of salvation, and all that is necessary for faith and life.
Westminster Confession of Faith 1.6 ↩︎
John Calvin, Institutes of the Christian Religion (trans. Robert White; Edinburgh: Banner of Truth, 2014), 464. ↩︎
Michael Horton, The Christian Faith: A Systematic Theology for Pilgrims On the Way (Grand Rapids, MI; Zondervan, 2011), 158. ↩︎
Sinclair Ferguson, The Authority, Sufficiency, Finality of Scripture. Quoted from https://www.monergism.com/authority-sufficiency-finality-scripture ↩︎
John Murray, O Death, Where Is Thy Sting? Collected Sermons (Philadelphia, PA; Westminster Seminary Press, 2017), 197. ↩︎