How necessary are extra-biblical sources for reading Scripture? Even for those who believe the Bible is Scripture, the text is assumed to stand behind a dense fog of historical distance and cultural isolation. I teach a class called Biblical Backgrounds to upper-level biblical and theological studies majors at Biola University, and it is by far my most dreaded class. I do not dread the class because the course is uninteresting or unimportant; on the contrary, I find extra-biblical sources like history and culture to be fascinating and think the class might be the most important one I teach. But it is important not because backgrounds gives necessary insights for the study of the Bible, but because it might be the most destructive tool for reading the Bible as Scripture.
I want to say this carefully, because I am the first to use backgrounds material in my reading of Scripture. Extra-biblical sources are dangerous because they remain unchecked, since the “meaning” of the text and its historical context are often inappropriately coalesced in the process of interpretation. The history behind the text is not the same thing as the text; and the Bible is far more than a text – it is Scripture (cf. The Death of Scripture and the Rise of Biblical Studies by Michael Legaspi, 2010). Ultimately it can only be the text – inspired Scripture – that is the final and arbitrating authority. At stake is not merely the control or influence of what can only be a reconstruction (a hypothesis or educated guess), but also the imposition of an alien or foreign authority on the Bible. Thus, the question for evangelicals is not "if" we use background material, for of course we do; the question is "how" do we use background material when interpreting Scripture.
I am currently writing a commentary on the Gospel of John for the Zondervan Exegetical Commentary on the New Testament series (Zondervan), and I use backgrounds in every passage. But as I write I am careful to interpret “John,” not the history or events to which he refers (cf.The Eclipse of Biblical Narrative by Hans Frei, 1974). John (and God) has already interpreted the history and events for me; there is no cleaner presentation or preferable perspective from which to stand than from within the confines of “John.” The attempt to get “behind” John to explore the history, culture, or events themselves would be not only to interpret something other than “John,” but to undermine the very presentation provided by “John,” that is, provided by God.
If you think the distinction I am making is confusing or trifle, please note the video that involves a pointed discussion on this very topic between my old exegesis professor at Trinity Evangelical Divinity School, D. A. Carson, and the well-known pastor from Bethlehem Baptist Church, John Piper.