John Webster, obviously, very much so appreciates Karl Barth, and in fact, he appreciates Barth’s idea on Scripture as “prophetic and apostolic testimony” (or Witness). But his appreciation is not without constructive critique and engagement. Here’s what he has to say, he is presenting various approaches to Scripture; this is his accounting of Barth’s:
Much less likely to beguile us into such problems is a third concept, namely that of Scripture as prophetic and apostolic testimony, much used by Barth throughout his writings, but found elsewhere in Reformed theology. What makes this a particularly helpful term is the way in which it retains the human character of the biblical materials without neglect of their reference to the Word and work of God. The very genre of ‘testimony’—as language which attests a reality other than itself—is especially fitting for depicting how a creaturely entity may undertake a function in the divine economy, without resort to concepts which threaten to divinise the text, since—like prophecy or apostolic witness—testimony is not about itself but is a reference beyond itself. However, some careful specification is needed, because the notion of Scripture as human testimony to God’s revealing activity can suggest a somewhat accidental relation between the text and revelation. This is especially the case when the essential unsuitability or creaturely fragility of the testimony is so stressed (in order to protect the purity of the divine Word) that there appears to be little intrinsic relation between the texts and the revelation to which they witness. In this way, the annexation of the Bible to revelation can appear almost arbitrary: the text is considered a complete and purely natural entity taken up into the self-communication of God. The result is a curious textual equivalent of adoptionism. If the difficulty is to be retarded, however, it has to be by careful dogmatic depiction of the wider scope of the relation between God and the text, most of all by offering a theological description of the activity of God the Holy Spirit in sanctifying all the processes of the text’s production, preservation and interpretation. Thereby the rather slender account of divine action vis-à-vis the text is filled out, without falling into the problems of undermining the creatureliness of the text which afflict talk of accommodation or the analogy of the hypostatic union.
Webster provides substance to some concerns that I’ve had in regards to Barth’s approach to Scripture. I’ve appreciated and even favored much of Barth’s thought, but not uncritically; and not whole-sale, it is nice to hear somebody who knows Barth as well as Webster does, provide a balanced appropriation and constructive critique of Barth. Webster employs the category of sanctification to provide a “place” for Scripture’s function within God’s mode of Triune speech and self-witness. In other words, instead of making Scripture the location for assuaging our epistemological needs; he places it within the realm of Revelation, which is co-ordinate with reconciliation. Meaning that God’s self-presentation penetrates our very beings, bringing us into His presence and recreates us through the activity of the Holy Spirit’s creativity and movement drawing us into the divine life through Christ. Scripture is attached to this self-communication of God as it is seen as the locale wherein the Spirit takes creaturely media (like our written word), and sanctifies these words in service to the Word of God who is God’s self-interpreting Word.
So in a nutshell: a doctrine of Scripture, according to Webster, should be under the category of soteriology vs. epistemology (by way of order); traditionally it is the other way around.
John Webster, Holy Scripture: A Dogmatic Sketch, 23-4.