Biblical theology for the most part is a Christian approach in which the theologian studies the Bible from the perspective of understanding the progressive history of God revealing Himself to humanity following the Fall and throughout the Old Testament and New Testament. It particularly focuses on the epochs of the Old Testament in order to understand how each part of it ultimately points forward to fulfillment in the life mission of Jesus Christ. Because scholars have tended to use the term in different ways, biblical theology has been notoriously difficult to define.

When Biblical theology seeks to understand a certain passage in the Bible in light of all of the biblical history leading up to it and later biblical references to that passage it is systematic, historical and dogmatic theology.

The Christian theologian asks questions of the text such as:Biblical theology seeks to put individual texts in their historical context since what came before them is the foundation on which they are laid and what comes after is what they anticipate. Biblical theology is sometimes called the "history of special revelation" since it deals with the unfolding and expanding nature of revelation as history progresses through the Bible.

The motivation for this branch of theology comes from such passages as Luke 24.27: "And beginning with Moses and all the Prophets, explained to what was said in all the Scriptures concerning himself." The assumption of this text seems to be that the Old Testament anticipated the messiah and that Jesus fulfilled those prophecies. Thus, Biblical theologians suggest that, in order to understand the intended meaning of a Biblical text, one must understand what the text points toward or back to. For instance, when reading about the sacrificial system in the Old Testament, Biblical theologians follow the trajectory the Bible lays out for that system (namely, pointing to Jesus as the true sacrifice), and likewise, when a New Testament text refers back to the Old Testament (for example, Jesus being the son of David and heir of his covenant), they try to understand that text against its proper, specified background.

Biblical theology can be compared with and is complemented by systematic theology, in that the former focuses on historical progression throughout the Bible while the latter focuses on thematic progression. Systematic theology deals with a single topic in each place it is dealt with, whereas biblical theology seeks to follow the flow of "redemptive narrative" as it unfolds. In this way, biblical theology reflects the diversity of the Bible, while systematic theology reflects its unity.

Though most speak of biblical theology as a particular method or emphasis within biblical studies, some scholars have also used the term in reference to its distinctive content. In this understanding, biblical theology is limited to a collation and restatement of biblical data, without the logical analysis and dialectical correlation between texts that Systematic theology emphasizes.

The Christian concept of progressive revelation differs from the Islamic understanding in which successive revelations of God might annul former revelations, completely replacing them with a new truth. The Christian model within biblical theology sees the concept of revelation as progressive; each new truth supports, expands, and stands upon former revelations of God's truth like brick laying. This progressive revelation ultimately climaxes in Christ, and ends with the New Testament acts of the Apostles under the direction of the Holy Spirit awaiting the Second Coming of Jesus.

Though the distinction existed prior, the beginning of biblical theology as a significant and separate discipline can be traced to J. P. Gabler’s 1787 address upon his inauguration as professor at the University of Altdorf, when he used the term and called for a separate discipline apart from the dogmatic emphasis of the confessions. This concern developed in the history of Israel's religion school, but the term eventually passed into its present usage.

Today, the discipline of biblical theology is primarily associated with viewpoints that also adhere to a belief in biblical inerrancy and biblical inspiration. Consequently, the work of Walter Brueggemann, Rudolf Bultmann, and other such scholars who reject these beliefs is not dealt with in the discipline . While it does engage with the work of philosophy and cultural and personal experience, it gives the Bible priority over each of these other lines of thought. Within this framework, biblical theology has been mostly carried out as either New Testament theology or Old Testament theology.

The work of Kevin Vanhoozer, Geerhardus Vos (Biblical Theology: Old and New Testaments), Herman Ridderbos (The Coming of the Kingdom), Meredith Kline (Kingdom Prologue) Graeme Goldsworthy (According to Plan, Gospel and Kingdom), and Vaughan Roberts (God's Big Picture) have helped popularize this approach to the Bible. They summarize the message of the Bible as being about "God's people in God's place under God's rule and blessing" (in Graeme Goldsworthy, Gospel and Kingdom, Paternoster, 1981).