Historians often describe the doctrine of Scripture, and particularly the authority of Scripture, as the formal cause of the Reformation. In philosophy, a formal cause is like a blueprint or plan; it is what determines the shape or form of something. To say that the final authority of Scripture was the formal cause of the Reformation is to say that the different views of biblical authority between the Protestants and the Roman Catholics explain why the Reformation took the shape it did. Because the Reformers believed Scripture is the only infallible authority for the church (sola Scriptura), they affirmed that church tradition and the bishops could be corrected by Scripture when Scripture conflicted with other authorities. Roman Catholics, on the other hand, said church tradition and the Magisterium (teaching officers of the church) were equal in authority to Scripture. Thus, Rome would not allow herself to be corrected on matters such as justification and worship, for their views on those issues were determined by extrabiblical traditions, which they believed had divine authority.
That Scripture stands above all other authorities is evident from just a cursory reading of the Bible. First, Scripture’s unique ontological (pertaining to being or essence) character as theopneustos—God breathed—means that every other authority is on a lower level by nature. By definition, God is the highest authority possible (Heb. 6:13), so what He says is the final arbiter of truth. And if the only place we have His words is Scripture, then Scripture is the highest court of authority to which we can appeal. Nothing else is on the same level, for only Scripture is theopneustos (2 Tim. 3:16–17).
Moreover, when we look at the example of Christ Himself, we find that He viewed Scripture as having the highest authority. In today’s passage, for example, Jesus says that “Scripture cannot be broken” (John 10:35). Other traditions and authorities can be set aside (Matt. 15:1–9), but “the doctrine of Scripture is inviolable” (John Calvin).
To say that Scripture is the only infallible authority and the final authority for the church does not mean there are no other authorities to which we should pay heed as believers. God does invest His church, for example, with authority as “a pillar and buttress of the truth” (1 Tim. 3:15). But other authorities are secondary, and their authority is derivative; they have the right to command us only insofar as what they teach conforms to the written Word of God.