Now Rome, with its infallible pope, can assert that Scripture is not necessary; the infalliblity of the church indeed renders Scripture superfluous. But Protestantism has no such infallible organ, neither in the institution, nor in the organism, nor in the individual members of the church. If Protestantism should deny the necessity of Scripture, it would weaken itself, strengthen Rome, and lose the truth, which is an indispensable element of religion. For that reason the Reformation insisted so firmly on the necessity of Holy Scripture. Scripture was the place for the Reformation to stand. It succeeded because, against the authority of church councils and the pope, it could pose the authority of God’s Holy Word. One who abandons this position of the Reformation unintentionally works for the upbuilding of Rome. For if not Scripture but the church is necessary to the knowledge of religious truth, then the church becomes the indispensable means of grace. The Word loses its central place and only retains a preparatory or pedagogical role. While Scripture may be useful and good, it is not necessary, neither for the church as a whole, nor for believers individually.
Reformed Dogmatics Vol. 1: Prolegomena (Grand Rapids, Michigan; Baker Academic; 2003) p. 469.