Doesn’t all this talk of theology just complicate matters that are already confusing enough? What is systematic theology? What is theology for that matter? In order for two people to have any kind of dialogue, they need a common vernacular and common ways to relate beliefs, thoughts, and concerns. That is where systematic theology proves its worth.
In Elwell’s “Evangelical Dictionary of Theology,” B.A. Demarest defines systematic theology in an abbreviated fashion as, “The attempt to reduce religious truth to a coherent and relevant whole for the church.” Later in his article, He expands the definition of theology:
“Theology might be more fully defined as the discipline that (1) presents a unified formulation of truth concerning God and his relationship to humanity as set forth primarily in divine revelation and secondarily in classical church teaching and the field of human knowledge and that (2) applies such truths to the entire range of human life and thought.”
This definition of systematic theology relates to other disciplines of theology such as biblical theology, historical theology, and philosophical theology by—as Demarest concludes—“incorporating” them all. However, before exploring these relations, it may be prudent to define biblical, historical, and philosophical theology.
Millard J. Erickson in “Christian Theology,” states that one can think of biblical theology as “the theological content of the Old and New Testaments, or the theology found within individual biblical books.” For example, one can look at the teachings of Paul across multiple epistles or isolate Paul’s specific message to an individual church. Either way, this is an example of constructing a biblical theology. Simply put, Erickson says biblical theology is a “theology that is biblical, that is, based on and faithful to the teachings of the Bible.”
Historical theology is the study of “how others have done it before us.” It looks at systematic theology through the lens of time. If biblical theology is the “raw material” from which systematic theology works, then “history is theology’s laboratory” where those materials can be observed. Historical theology offers the invaluable attribute of hindsight.
Erickson expounds that philosophical theology may “(1) supply content for theology, (2) defend theology or establish its truth, and (3) scrutinize its concepts and arguments.” If we envision systematic theology as a product, philosophical theology would be the research and development step in the process of producing said product. It is the step that tests, weighs, and hones the prototype. Ultimately, this step improves the product and readies it for release.
Systematic Theology in Relation to Biblical Theology
Systematic theology relates to biblical theology by being “dependent on the work and insights of the laborers in the exegetical vineyard.” As Erickson puts it, “biblical theology is the raw material” from which systematic theology draws its conclusions. To remove, alter, or nullify the source, would be absolutely detrimental to systematic theology. Systematic theology really starts from biblical theology. It grows from its rich soils.
Systematic Theology in Relation to Historical Theology
Systematic theology relates to historical theology by allowing its practitioners to delve into the annals of time and glean important insights, learn from past mistakes, and study pathways blazed by previous generations. By employing historical theology, modern readers can draw upon Christianity’s rich heritage. As Erickson remarked, “The study of the theologizing work of a John Calvin, a Karl Barth, or an Augustine will give us a good model and should inspire us in our own activity.” Historical theology also allows contemporary theologians the luxury of crosschecking to distinguish if cutting-edge ideas are really just “new forms of old conceptions.”
Systematic Theology in Relation to Philosophical Theology
Erickson explains that systematic theology relates to philosophical theology in the sense that it “may serve to justify in part the endeavor in which theology is engaged.” That is to say, it appraises any claims, terms, or ideas and attempts to “sharpen the message for clarity.” Philosophical theology is a bit of an “odd man out” with this group so to speak. As Erickson remarks in his footnote of this section, “Although philosophy cannot prove the truth of Christian theology, it can evaluate the cogency of the evidence advanced, the logical validity of theology’s arguments, and the meaningfulness or ambiguity of the concepts.” Therefore, it can measure the evidence but not prove it either way.
The Most Important Theology-type in My Current Ministry
Any proper ministry will be well rounded by borrowing from and partnering with each of these schools. As Demarest says, “they are overlapping disciplines.” However, systematic theology as it relates to biblical theology is the most important in context to my own personal ministry. It may seem redundant to state that I desire for my theology to be biblical, but (strangely and sadly enough) this is not the case with every ministry one may encounter. The gospel of Christ is the power of God (Rom. 1:16) and I can think of no higher source from which to draw.
 Bruce Demarest, “Systematic Theology,” in Evangelical Dictionary of Theology, 2nd ed., ed. Walter A. Elwell (Grand Rapids: Baker Academic, 2001), 1,162.
 Ibid., 1,164.
 Millard L. Erickson, Christian Theology, 3rd ed. (Grand Rapids: Baker Academic, 2013), 11.
 Ibid., 13.
 Ibid., 12.
 Ibid., 13.
 Ibid., 14.
 Ibid., 10.
 Ibid., 12.
 Ibid., 13.
 Ibid., 14.
 Bruce Demarest, 1,163.
Demarest, Bruce “Systematic Theology,” in Evangelical Dictionary of Theology. 2nd ed. Walter A. Elwell. Grand Rapids: Baker Academic, 2001.
Elwell, Walter A., ed. Evangelical Dictionary of Theology. 2nd ed. Grand Rapids, MI: Baker Academic, 2001.
Erickson, Millard J. Christian Theology. 3rd ed. Grand Rapids: Baker Academic, 2013.
Submitted to Liberty University Baptist Theological Seminary in partial fulfillment of the requirements for the completion of the course THEO 525 Systematic Theology I