“[N]ormative (as opposed to historical or descriptive) biblical theology attempts to give a comprehensive account of the theological teaching of Scripture as a whole, and of the claims made by that teaching upon the mind and practice of the church of Jesus Christ. It undertakes this task on the basis of a conviction that, in the economy of God’s revelatory and reconciling presence, such an account is both necessary and possible. It is necessary because the truthfulness and legitimacy of the church’s thought and action rest upon its openness to divine instruction in its fullness and integrity: as such, biblical theology is a corollary of tota scriptura. It is possible, first, because in all of their variety the biblical writings together constitute a unified divine act of communication—a single, though a rich, complex and historically extended, divine word from which a coherent body of teaching can be drawn. From this perspective, biblical theology is a corollary of the unity of Scripture as the church’s canon. And a comprehensive biblical theology is possible, second, because the coherent teaching that Scripture sets forth can be discerned by the Spirit-directed use of interpretative reason in the communion of saints. The possibility of biblical theology is, therefore, a corollary of the clarity of Scripture.
“Affirming the viability of a comprehensive biblical theology is thus closely related to making judgments about the nature of Scripture. These include judgments about whether terms like ‘Scripture’ or ‘canon’ identify properties of the biblical texts in relation to God or simply indicate churchly use, or judgments about whether the distinction between the Old and New Testaments indicates episodes in the single drama of God’s revelatory grace, or only a more or less awkward juxtaposition of two religious systems and their textual carriers. At least since Gabler, historians of biblical literature and religion have characteristically argued that canon, unity or clarity are dogmatic judgments, arbitrary impositions upon the biblical materials which cannot be warranted by historical description. These historians have, accordingly, been reluctant to develop a comprehensive biblical theology. From the vantage point of Christian dogmatics, overcoming such reluctance will require an account of the unity, canonicity and clarity of Scripture in relation to the economy of God’s communicative grace and its reception in the church.”
—John Webster, “Biblical Theology and the Clarity of Scripture,” in Out of Egypt: Biblical Theology and Biblical Interpretation, ed. Craig Bartholomew, Mary Healy, Karl Möller, and Robin Parry (Grand Rapids: Zondervan, 2004), 352-384, at 352-353