The sufficiency of Scripture is closely related to the inspiration and authority of the Bible. When we speak of the inspiration of Scripture, we refer to the fact that the various books of the Bible have their origin in the will of God. The books of the Bible have been breathed forth by God the Holy Spirit through the agency of human writers (2 Timothy 3:16). When we speak of the authority of the Bible, we mean that since the Holy Spirit is Scripture’s divine author, the Holy Spirit is alone able to bear witness to the truthfulness and divine origin of God’s word. The church does not give the Bible its authority. Rather, the church can only recognize that authority which Scripture already possesses because God has breathed it forth.
When we speak of Scripture as “sufficient,” we mean that the Bible reveals everything God wants us to know about his will, and how to be saved from his wrath. The Bible was given for a very specific purpose. The Bible does not teach us everything that might be useful or practical to know, nor was it intended to do so. The Bible was not given to satisfy sinful human curiosity, nor will we find answers to all of the mysteries of life. The secret things belong to God (cf. Deuteronomy 29:29).
But the Bible does reveal both the law and the gospel. The law is that which God commands of us and is found in a passage such as Exodus 20 (the Ten Commandments). The gospel is what God gives to us in Jesus Christ which meets the demands of his law, and is spelled out by Paul in 1 Corinthians 15:1-8 (as but one example). Although the moral law is universal–it us written upon our hearts because we are created in God’s image–only in the Bible do we find God’s law in written form so that God’s will is perfectly clear to all.
While the beauty and wonder of creation powerfully points us to the creator–so much so that we cannot deny God’s existence–the story of God’s saving work to rescue sinners through the person and work of Jesus Christ is not written in the beauty of mountain peaks, nor is it found in the awesome crashing of the seas. The only place where we will find the gospel is in the word of God written.
When we speak of the sufficiency of Holy Scripture, we mean that in the Bible we find the account of our redemption which unfolds in the covenant of works made in Eden with Adam, and which is restated in the Ten Commandments, as well as through the various administrations of the covenant of grace in which we witness Jesus save us from our sins in the types and shadows of the Old Testament, and in the promise and fulfillment of the New. Since this story of redemption is the content of the Bible, what else could we possibly need to know about how to worship God properly? What else do we need to know about how to be delivered from the guilt and power of sin that God has not already revealed to us in his word? Do we need church tradition to clarify the gospel? Do we need additional “holy books,” or “revelations” to reveal those things supposedly missing from the Bible? Of course not.
In the Bible we have all that we need to know God’s will and to be saved. As justified sinners who are cleansed by the blood of Christ and clothed in his perfect righteousness, we are free to approach the Holy God with thankful hearts, and worship him in the manner he prescribes. But we only know this because the Bible reveals this to us. This is what we mean when we say “Scripture is sufficient.”