The third pillar of the Reformation is Sola Scriptura, by Scripture alone. Scripture is the only source of authority for things pertaining to salvation and the Christian faith and life, and it is infallible. Although there are not Bible passages that use this expression the way there are with by grace alone and through faith alone, Scripture does clearly teach this truth as well. Isaiah 8:20 says, “Consult God’s instruction and the testimony of warning. If anyone does not speak according to this word, they have no light of dawn.” Thus, anything that does not match up with what God says has no light and no truth to it.
That the Scriptures are the very Word of God is expressly stated. The prophets often included phrases that highlight that this was really God speaking when they say, “The word of the Lord came to me” and “Thus says the Lord.” The apostle Peter also proclaimed in 1 Peter 1:19-21: “We also have the prophetic message as something completely reliable, and you will do well to pay attention to it, as to a light shining in a dark place, until the day dawns and the morning star rises in your hearts. Above all, you must understand that no prophecy of Scripture came about by the prophet’s own interpretation of things. For prophecy never had its origin in the human will, but prophets, though human, spoke from God as they were carried along by the Holy Spirit.”
In 2 Timothy 3:16-17, the apostle Paul stated this same truth: “All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness, so that the servant of God may be thoroughly equipped for every good work.” And since Scripture alone is the very Word of God, nothing else is on par with it or even comes close. Reason, tradition, and experience can be helpful, but they never have equal weight with what God himself says. In order for them to be beneficial, they must agree with God’s Word.
God’s Word doesn’t tell us everything there is to know, but it does tell us everything we need to know. It tells us that we are saved by grace alone, through faith alone in Jesus Christ alone, and that’s the truth!