Whereas patristic, medieval theologians, and early Reformed confession began with God as the starting point for theology (e.g. Apostles’s Creed; Origen, First Principles; John of Damascus, Orthodox Faith; Anselm, Prologion; Peter Lombard, Sentences; Aquinas, Summa Theologica; Augsburg Confession; Calvin, Institutes; Scot’s Confession; Tetrapolitan Confession), it was the Second Helvetic Confession, followed by the Irish Articles and Westminster Confession, that broke the mold by putting the doctrine of Scripture first in the order of topics covered in theology. This Protestant move is understandable, opposing as it does the medieval Roman Catholic view of authority; yet it was a misstep that ultimately led to a shift from theology beginning with God-in-himself to theology beginning with human reception/perception of revelation.
D. A. Carson and Tim Keller (Gospel-Centered Ministry [Wheaton, IL: Crossway, 2011], 6-7) make a great point of this that any theology should start with God rather than with doctrine of Scripture:
We also thought it was important to begin our confession with God rather than with Scripture. This is significant. The Enlightenment was overconfident about human rationality. Some strands of it assumed it was possible to build systems of thought on unassailable foundations that could be absolutely certain to unaided human reason. Despite their frequent vilification of the Enlightenment, many conservative evangelicals have nevertheless been shaped by it. This can be seen in how many evangelical statements of faith start with the Scripture, not with God. They proceed from Scripture to doctrine through rigorous exegesis in order to build (what they consider) an absolutely sure, guaranteed-true-to-Scripture theology. The problem is that this is essentially a foundationalist approach to knowledge. It ignores the degree to which our cultural location affects our interpretation of the Bible, and it assumes a very rigid subject-object distinction. It ignores historical theology, philosophy, and cultural reflection. Starting with the Scripture leads readers to the overconfidence that their exegesis of biblical texts has produced a system of perfect doctrinal truth. This can create pride and rigidity because it may not sufficiently acknowledge the fallenness of human reason. We believe it is best to start with God, to declare (with John Calvin, Institutes 1.1) that without knowledge of God we cannot know ourselves, our world, or anything else. If there is no God, we would have no reason to trust our reason.
On the place of a doctrine of Scripture in systematic theology, see John Webster, Holy Scripture: A Dogmatic Sketch (Cambridge: CUP, 2003), 12; Timothy Ward, Words of Life: Scripture as the Living and Active Word of God (Nottingham, UK: Apollos, 2009), 14–18; Andrew T. B. McGowan, Divine Spiration of Scripture (Nottingham, UK: Apollos, 2007), 26-28.