When I first heard this term a number of years ago, I thought it was making the statement, “This here is Biblical theology where as systematic and doctrinal theology is not.” I assumed this based on the anti-intellectualism that seems to characterize so much evangelicalism, where people say, “I don’t need doctrine or theology I just need what the Bible says.” Soon did I realize the phrase Biblical theology had nothing to do with this. In sum, Biblical theology deals with the linear, historical progression of God’s revelation of redemption, summed up in Jesus, culminating at the end of the age when God judges the world in Christ. Instead of systematic theology, where we go through and categorize specific doctrines (the nature of God, the trinity, atonement, resurrection, election, church government, etc), Biblical theology entails these things, but more specifically within the context of history, and even broader than that what God is doing and has done in history to bring about redemption. This approach to Scripture is highly important in preaching and teaching so that we see the fullness of what God is doing in proclaiming His glory and perfect righteousness to a dying world. Here are a couple of quotes on Monergism.com’s section on Biblical theology that gives a very good explanation:

Kerux – A Primer on Biblical Theology

Biblical Theology approaches the Bible as an organic drama of God’s unfolding revelation through history. In distinction from doctrinal or systematic theology, biblical theology follows the progressively unfolding revelation of God’s words and deeds through history. This linear aspect of revelation unites each revelatory event and proclamation both retrospectively and prospectively. Geerhardus Vos described the organic continuation of revelation in history as a flower expanding from bud to blossom. The blossom is retrospectively united to the bud; the bud is prospectively united to the blossom. One of the tasks/privileges of the interpreter of Scripture is to draw out these organic prospective and retrospective relationships. At the center of this organic unity is the person and work of our Savior, Jesus Christ. Even as our Risen Lord related all of Scripture retrospectively and prospectively to himself (Luke 24:27), so Reformed biblical theology is preeminently Christocentric.

God spoke into history; God acted in history; God was incarnated in history. Vos described this vertical interface with history as the eschatological penetration of the history of redemption. In fact, Vos approached Scripture from the standpoint of the priority of the eschatological. Overarching the entire history of redemption was the eschatological arena. Every revelation of God in history was an invitation for the creature to possess the arena of the Eschatological/heavenly. This would only be accomplished through the saving work of the Son, Jesus Christ. Hence, Christ was eschatologically revealed throughout the history of redemption as the promised seed of the woman, seed of Abraham, seed of Jesse, etc. Even as God and man met in Jesus Christ, so the eschatological and the linear met at every point of God’s special revelation.

Graeme Goldsworthy – Preaching the Whole Bible as Christian Scripture

From the evangelical preacher’s point of view, biblical theology involves the quest for the big picture, or the overview of biblical revelation. It is of the nature of biblical theology that it tells a story rather than sets out timeless principles in abstraction. It does contain many timeless principles, but not in abstract. They are given in an historical context of progressive revelation. If we allow the Bible to tell its own story, we find a coherent and meaningful whole.

9Marks Ministries Introduction page to Biblical Theology:

Here is a link to Monergism’s page on Biblical theology:
http://www.monergism.com/directory/link … -Theology/