For nearly 20 years now, “The Big Blue Book” (also known as Wayne Grudem’s Systematic Theology) has found its way onto evangelical shelves, church libraries, and college classrooms. Now, thanks to The Southern Baptist Theological Seminary professor of Christian theology Gregg Allison, we have “The Big Green Book”—Historical Theology: An Introduction to Christian Doctrine—a companion volume to Grudem’s work. I corresponded with Allison to learn more about this long-awaited work and learn why evangelicals ignore historical theology at their own peril. Allison discusses why the early church taught the the ransom theory of the atonement, whether we can find true spiritual kingship with Christians before the Reformation, and why we should become as familiar with Thomas Aquinas as we are with Mark Driscoll.

How do you explain the importance of historical theology to skeptical evangelicals?

Some evangelicals are skeptical of historical theology because they hold to the motto “No creed but the Bible” and thus reject input from any source other than Scripture. My approach to historical theology is to view it as offering wisdom from the past in terms of the interpretation of Scripture and the formulation of sound doctrine (which is enjoined upon us by Scripture; e.g., Titus 2:1). God has promised to guide his church, and historical theology must represent an aspect of that promised guidance.

I also try to point out that even they as skeptical evangelicals reply on historical theology for their articulation of the doctrine of the Trinity and their affirmation that Jesus Christ is both fully God and fully human. Those beliefs—and these are used as representative of many other possible examples—have been hammered out by the church of the past and transmitted down to us as sound doctrine (chiefly because they accord well with and summarize accurately the teachings of Scripture), and anyone who dares deny them would be a heretic. Skeptical evangelicals—and all Christians, for that matter—are helped to embrace orthodoxy (sound doctrine) and avoid heresy (false doctrine) by historical theology.

It is possible for us as evangelicals to read historical theology and find real spiritual kinship with Christian forebears, even before the Reformation and evangelical awakenings?

Both spiritual kinship and stellar examples of faith, love, courage, hope, obedience, and mercy! How can we not be encouraged by the examples of martyrs in the earliest centuries of the church, people like Polycarp, Perpetua, and Felicitas who preferred death for the sake of Christ over renouncing Christ and living? How can we not be emboldened to champion the truth by the example of Athanasius, who suffered five exiles for the sake of defending the belief that Jesus Christ is fully God? How can we not be convicted of our own perversity by the frank confession of Augustine that the only reason he stole pears from a garden was for the sake of sinning?

Read historical theology and experience the richness of Christian community across the centuries.

How did you decide what to exclude in this textbook that’s long but cannot be comprehensive?

The many decisions between what to include and what to exclude constituted one of the most difficult aspects of writing this book. Two principles—put in the form of a question—guided my decision-making process in most cases: (1) Is this a major contribution to the historical development of the doctrine? If so, then I would include it. For this reason, readers will find me going back chapter after chapter to the same theologians and church leaders—Irenaeus, Tertullian, Augustine, Anselm, Martin Luther, John Calvin, John Wesley, Karl Barth—because their contributions were so weighty for doctrinal developments at their time. (2) Is this contribution reasonably accessible to my readers so that they might easily do follow up reading or research about it? I hope to stimulate Christians in general and evangelicals in particular to do further explorations in the primary sources cited throughout my book, and by choosing readily available resources, I believe my book will facilitate such further study.

Where and how do you envision this book being used?

Here is how it is being used already: (1) Christians who are deepening their understanding of theology are drawn to understand how the church has come to believe what it believes today. Accordingly, they are starting with chapters of particular interest—e.g., the inspiration of Scripture—and reading them to grasp the historical development of these doctrines. (2)  People who are familiar with Wayne Grudem’s Systematic Theology: An Introduction to Biblical Doctrine (to which my Historical Theology is a companion) are going back to read his theology of, say, the person of Christ (ST, ch. 26), then turning to my book to read the historical development of that doctrine (HT, ch. 17). For those interested in using this reading strategy, I have provided a helpful chart (HT, pp. 19-20) for using these two companion volumes for greatest benefit.

In an educational setting, I envision my book being used as supplemental reading in systematic theology courses, providing students with an introduction to how the doctrines they are studying came about historically, and as a textbook in church history and historical theology courses.

Give us an example of something evangelicals might be surprised to read in Historical Theology.

In the early church, one of the major ideas of what Christ’s death accomplished—such ideas are called theories or models of the atonement—was that it was a ransom paid to Satan, who had usurped God’s rightful ownership of human beings; thus, all people illegitimately belong to Satan. Christ’s death was the ransom that was paid to release people from this tragic situation. Once Satan had Christ in his clutches, however, he could not hold him; indeed, God tricked Satan, causing the loss of his victim. The deception was due to Christ’s deity being enclosed in human flesh. Lured by the powerful miracles of Christ, Satan desired to conquer him as the ransom for humanity. But Satan was tricked, for he had no idea that hidden under Christ’s flesh was the divine nature. By means of the resurrection of Christ, Satan lost not only his former slaves, who had been ransomed by Christ, but also the ransom—Christ himself.

This idea was very popular in the first millennium of the church, but it later gave way to other and—we would assess—more biblical models of the atonement. But notice what was going on: the church corrected its earlier view because as the church progressed in its reflection on this work of Christ for salvation, it realized that the ransom to Satan theory did not accord well with Scripture. We evangelicals can learn a great deal from this methodology!

Surely you must have learned a great deal composing this volume. What stands out?

I’ll concentrate on two lessons. First, to a great degree, the early church laid down the foundations on which evangelical Christians and churches should build their beliefs and practices today. Early church theology was amazingly rich and fruitful!

Second, the modern period has featured virulent attacks against every traditional doctrine held dearly by the church of the past, with the result that evangelical Christians and churches must go back to Scripture and historical theology for their moorings. This attitude is not one of pining for some (non-existent) golden age in the past. Rather, it is a frank admission that given these modern assaults, we must be particularly vigilant for sound doctrine, we must be wary of reformulations of doctrine that bear little or no resemblance to the historical legacy of the faith, and we must lean on Scripture and wisdom from the past. We should also pray that God will raise up—as he has always done—apologists and other church leaders who will articulate and defend “the faith that was once for all delivered to the saints” (Jude 3).

Do you really think evangelicals can and should be as familiar with Thomas Aquinas as they are with Mark Driscoll, as you write in the preface?

I bet Mark Driscoll would agree with me! He is a staunch proponent of sound doctrine and is attempting to articulate and defend it with a particular method well-suited for his contemporary audience and with a missional focus. Just look at the titles of his books (written with Gerry Breshears): Doctrine: What Christians Should Believe; Vintage Jesus: Timeless Answers to Timely Questions; and Vintage Church: Timeless Truths and Timely Methods. Thomas Aquinas was a staunch proponent of sound doctrine—notice how often he quoted Augustine and other early church theologians—who attempted to articulate and defend it with a particular (Aristotelian) method well-suited for his medieval audience and with a missional focus. Just look at his masterpiece—Summa Theologica, or summary of theology. And don’t overlook his Summa contra Gentiles, a manual for missionaries working among Jews and Muslims, providing support for the Christian faith.

Evangelicals can learn much from Aquinas: his careful reasoning, his appeal to Scripture, his attempt to use philosophy for the benefit of theology, his interaction with historical theology, his championing of sound doctrine, his contextualization of the faith, and much more. Why would we intentionally ignore such help as we seek to do much of the same in our contemporary society? Read Aquinas. Read Driscoll (or at least listen to his podcasts). We will progress further as result of both.

Other than your work, where else do you suggest we turn to learn more about historical theology?

A wonderful set of books is Jaroslav Pelikan, The Christian Tradition: A History of the Development of Doctrine, 5 vols. (Chicago and London: University of Chicago Press, 1971-1991). An essential collection that brings together the creeds of the church is Philip Schaff, Creeds of Christendom, 3 vols. (New York: Harper, 1877-1905). For work in the early church, the standard materials are the Ante-Nicene Fathers (10 vols.), Nicene- and Post-Nicene Fathers, 1st series (14 vols.), and Nicene- and Post-Nicene Fathers, 2nd series (14 vols.). These three sets are all available electronically. I’ll finish the list—which could go on much longer—with the indispensable Library of Christian Classics, 26 vols. (Philadelphia: Westminster, 1960).

My Historical Theology will orient its readers to the most important sections of all of these works, as I constantly make reference to them.