Because no one really knows what it is.
Yesterday I was asked the same question for the umpteenth time: Just what is tBiblical Theology? The question is notoriously difficult to answer. Ask five theologians and you will get 13 answers. It seems that in the fields of Biblical Studies and Theological Interpretation there is no king in Israel so every man does that which is right in his own eyes. Biblical Theology is still a veritable Babel; a cacophonous Upper Room still waiting for the Spirit of Illumination to sort us all out.
For my purposes as a scholar who would identify historically as a Protestant, theologically as a Reformed Catholic, philosophically as a conservative, and ecclesially as an Anglican, I would reject any a priori methodological assumptions which were based on upon the authority of an absolute Mortal Magisterium or rooted in the various forms of rationalistic Higher Criticism or the so-called, “Hermeneutics of Suspicion.” I begin with an unflinching and unqualified allegiance to the Living Word of God. This is not a leap of faith—my feet have never moved. From a child I have known the Holy Scriptures; those very oracles which made me wise unto salvation through faith in Jesus Christ. I am simply continuing in the things which I have learned and have been assured of, knowing from whom I learned them. As someone walking around with God’s air in my nostrils it would be awfully presumptuous of me to doubt the vivifying power of God’s breath in His own book.
That said, how do I set about the task of answering the question? As a good Trinitarian I think that I can sum up my approach under three headings. Interestingly, each heading is somehow rooted in the missions of God (but that takes us into Systematic Theology territory so I digress). This is just a working definition, not a full explanation. Think of it as an interim report.
Biblical Theology is Covenantal in its framework.
This is predicated on the assumption that God the Father has dealt with His creation through a series of divinely initiated covenants which are progressively revealed throughout redemptive history in the pages of Sacred Scripture. This assumption is grounded upon another theological assumption; namely that the inner life of God is essentially covenantal ( Pactum Salutis, Perichoresis, etc.). *You must forgive me. I was trained as a systematician first so my process tends to seek to internally integrate the disciplines instinctively.
Biblical Theology is Christological in its focus.
This is predicated on the assumption that God the Son is the locus of the supreme Divine Self-Disclosure. Since all of God’s economic activity in both creation and redemption is both actuated by and centered around the Son, God has providentially ordered all of human history (and His revelation of Himself as part of that redemptive activity) to point to and find its culmination in the person and work of Jesus Christ. To borrow the words of Hopkins and wax poetic:
“Christ plays in ten thousand places,
Lovely in limbs, and lovely in eyes not his
To the Father through the features of men’s faces.”
Biblical Theology is Canonical in its form.
This is predicated on the assumption that God the Holy Spirit has infallibly ordered all of Holy Scripture—down to the smallest jots and tittles—so as to carefully preserve the structural integrity and theological coherence of all of its parts. This allows, if not demands, the reader to attempt to read all of the Bible through the lens of all of the Bible. On this principle the literary features of the text are as important as the lexical features. Historical events, persons, and places are filled full with spiritual significance. Names and numbers, topology and typology, and symbols and signs all rise to levels of importance so that there are no insignificant details. Like the Triune God who inspires it, Holy Scripture reveals its majesty by manifesting a glorious unity in diversity.