Systematic Theology is often contrasted unfavourably with the relatively new discipline of Biblical Theology. The very terminology immediately sets Systematics at a disadvantage, as if Biblical Theology alone were 'biblical' and anything that sets out to be 'systematic' should be viewed with profound suspicion. At one time in his career Karl Barth even refused to lecture on 'Systematic Theology' because, he argued, the combination of this noun and this adjective was highly problematical. Many Evangelicals share Barth's suspicions, often for the same reasons. 'System' conjures up the notion of alien philosophical ideas imposed on the concepts of Scripture; or, alternatively, a theology confined within a confessional straitjacket.

 

To others, 'systematic' suggests the imposition of human logic on divine revelation. But, then, would it be better to be illogical? After all, as Don Carson points out, the laws of logic were not inventions of Aristotle, but inescapable conditions of all human thought and communication. [1]  Besides, if logic and inference aren't allowed, what are we to make of Paul's many 'therefores'? 

Yet others are suspicious because they associate Systematic Theology with the idea of imposing some master-concept (for example, predestination) on biblical truth and manipulating everything else around it; or because it implies a fixity and finality which no human construct should ever claim (though it would be hard to find a Systematic Theologian who has never for cover to the watchword, semper reformanda); or, finally, that Systematic Theology is inherently abstruse and far removed from the pressing concerns of Christian discipleship (even though Calvin's Institutes contain a brilliant treatment of 'the life of a Christian man', embracing such topics as self-denial, cross-bearing, meditating on the future life, prayer and Christian liberty;  and most Reformed compendia of theology include discussions of such experiential realities as faith, repentance and assurance). [2]

But 'systematic' and 'biblical' are not, surely, mutually exclusive? The opposite of 'systematic', after all, is not 'biblical' but 'un-systematic' (or chaotic!). The truth is both that Biblical Theology is systematic and that Systematic Theology is biblical. As Carson points out, 'the proper data base for systematic theologians is the Bible' ('Unity and Diversity' p. 82); and however desperate Biblical Theologians may be to escape from the 'straitjacket of Systematic Theology' they instinctively use its categories. For example, the Biblical Theology of Geerhardus Vos, who once taught Systematics but is best remembered as a pioneer of Biblical Theology, offers extensive treatments of such topics as 'The Nature and Attributes of Jehovah', 'Prophetic Eschatology', and 'Jesus' Doctrine of God'. Eichrodt's Theology of the Old Testament, though written from a very different perspective, proceeds in exactly the same way, lingering over such topics as 'The Name of the Covenant God', 'The Nature of the Covenant God' and 'Cosmology and Creation'. Both works are in the highest degree systematic as well as biblical. Indeed, the distinction between Biblical and Systematic is itself a form of systematisation; and not one laid down in the Bible, but one adopted as a matter of academic convenience. It reflects no more than two different ways of looking at the same biblical material.

What, then, are the differences? 

The most obvious is that while Biblical Theology adopts a chronological approach, tracing the history of revelation, Systematic Theology approaches the Bible as a finished product in which God has spoken his last word (for the present). This is why we can have separate Biblical Theologies for the Old and New Testaments: the one follows the other on the time-line. This is also why within the Old we have separate treatments of the Patriarchal, Mosaic and Prophetic revelations, and why even within the New we can trace the progress of revelation from the synoptic gospels to the early preaching in Acts through to the theology of the Pauline epistles and finally the writings of the Apostle John. It is implicit in this that none of the earlier eras is final. This is why Calvin can write, in his Commentary on Hebrews 8:8, 'the Old Testament was amended by the coming of Christ.' Some of its provisions (for example, the Levitical sacrifices and the food-laws) were clearly provisional, and destined to be superseded by later revelation.

The preference for Biblical Theology reflects what moderns like to think of as the 19th century emergence of 'historical consciousness', requiring us to see everything in context. This consciousness has sometimes produced an unwelcome relativism, but in the case of Scripture, it is fully justified. Divine revelation is not only given in history, but has a history: a history which is intertwined with the progress of redemption itself. It was precisely because God acted 'at sundry times and in divers manners' that he also spoke 'at sundry times and in divers manners' (Heb. 1:1, KJV). But he also spoke progressively, revealing himself gradually and cumulatively. 

The history of this revelation is not, however, the story of the ever-greater achievements of human theological enquiry, or the gradual 'evolution' of the religion of Israel, or the developing 'insights' of the early church. It is the story of God's progressive unveiling of himself, accommodating himself to what Calvin called 'the rudeness of his ancient people' [3] and leading us ever further into God's 'secret' until, in the Last Days, the revelation culminates in the wonder of the incarnation. 

Biblical Theology recognises this time-line and systematises its material on a chronological principle, tracing the story of revelation from the Patriarchs to the Last Days. Yet we must never forget that what to us is the last word is, in reality, only the provisionally last: the last word for the present. Even with the complete written revelation in our hands we see only through a glass, darkly (1 Cor. 13:12). God still has much more to say and much more to show, but that must wait till we see him face to face. Then revelation will proceed on a new time-line, world without end.

This fact of the historical nature of revelation presents its own challenge to the preacher, particularly when preaching from the Old Testament. Whatever text we are expounding, we must always ask, Where does this man stand in the history of revelation? How much did he know, and how much did he not know? We must even ask, in the light of 1 Peter 1:11, How much of what he was saying did he actually understand? We cannot assume, for example, that when Job declared, 'I know that my redeemer lives' (Job 19:25) he was already in full possession of all that the Apostle John saw in his vision of the Lamb on the Throne (Rev. 5:6-10). 

On the other hand, this should not have the effect of lowering the Old Testament saints in our estimation. Quite the contrary! The wonder is that such believers as Job and David, with so much less light on life after death and so much less clarity on the identity of the promised Messiah and the glory of his work, yet showed such remarkable resilience, courage and hope. The preacher must always move on to argue, How much more is expected of us who enjoy so much fuller a revelation!

Systematic Theology, by contrast with Biblical Theology, approaches the Bible as a completed divine revelation, taking account of all that has been said and carefully noting what has been superseded and what is 'truth unchanged, unchanging'. This means that Systematic Theology gratefully accepts and assimilates all that Biblical Theology has to offer. But it also recognizes in Biblical Theology that its words are not final. The Psalms may speak truth and nothing but the truth, but they are not God's last word. This is why a chapter on 'The Eschatology of the Psalter', however stimulating, cannot be equated with 'The Eschatology of the Bible'. The same applies to the writers of the New Testament. While Paul and John both speak the truth and nothing but the truth, neither of them speaks the whole truth. For all the grandeur of his Prologue, John does not say all that has to be said on the incarnation. Neither does Paul, for all the vehemence of his Galatians, give us the whole truth about justification, any more than any one of the four gospels contains the whole canonical story of Jesus' life on earth. The whole truth (or what God wishes us to know in the meantime) can be ascertained only by collating all that has been said, incorporating the perspectives of all the biblical writers, and sifting the permanent from the transitional. 

This is what gives Systematic Theology its finality. Biblical Theology asks, What did the patriarchs say, or Moses, or the prophets or Paul or John? Systematic Theology asks, What does the Bible say?

The second difference between Biblical Theology and Systematic Theology is that they proceed from different premises. The former presupposes the diversity and variety of Scripture; the latter, its underlying unity.

Of which, perhaps, more later.

Donald Macleod is Professor of Systematic Theology at the Free Church of Scotland College, Edinburgh, Scotland. He is the author of A Faith To Live By (Christian Focus, 1998), The Person of Christ (IVP, 1998) and Christ Crucified (IVP, 2014)

[1] D.A. Carson, 'Unity and Diversity in the New Testament: The Possibility of Systematic Theology' in D.A. Carson and John D. Woodbridge (eds), Scripture and Truth (Leicester: IVP, 1983), p. 80.

[2] Calvin, Institutes III, iv-xx

[3] Calvin, Commentaries on the Last Four Books of Moses, vol. 2 (Edinburgh: Calvin Translation Society, 1853), p. 198.