Because scholars have tended to use the term in different ways, Biblical theology has been notoriously difficult to define. Description Although 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. Mark Bowald, writing for Grace Theological Seminary, stated that "four areas of focus" of theology "include biblical theology, historical theology, systematic (or dogmatic) theology, and practical theology". Although 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. Some scholars focus on the Old Testament or Hebrew Bible and falls in the field of Old Testament theology. The field started out as a Christian endeavor and aimed to provide an objective knowledge of early revelation, working as much as possible only with these biblical texts and their historical contexts, in the twentieth century it became informed by other voices and views, including those of feminist and Jewish scholars, which provided new insights and showed ways that the early work was bound by the perspectives of their authors. Key scholars have included Walther Eichrodt, Gerhard von Rad, Phyllis Trible, and Jon Levenson. Others focus on the New Testament; the field of New Testament theology likewise seeks understanding from within the bounds of these documents and their historical contexts. Key scholars have included Rudolf Bultmann, Hendrikus Boers, and N. T. Wright. Evangelicalism In Evangelicalism, biblical theology is a discipline of theology which emphasises the progressive nature of biblical revelation. Graeme Goldsworthy explains the relationship between biblical theology and systematic theology as follows: The work of Gregory Beale, Kevin Vanhoozer, Geerhardus Vos (Biblical Theology: Old and New Testaments), Herman Nicolaas Ridderbos (The Coming of the Kingdom), Meredith Kline (Kingdom Prologue), Graeme Goldsworthy (According to Plan, Gospel and Kingdom), Vaughan Roberts (God's Big Picture), James Hamilton (God's Glory in Salvation through Judgment), and Peter Gentry and Stephen Wellum (Kingdom through Covenant: A Biblical-Theological Understanding of the Covenants) have helped popularize this approach to the Bible.