What Systematic Theology Is

Systematic theology asks what the whole Bible teaches on a subject, and arranges the answer so that a believer can hold it and act on it. That is the definition this track will work with, and every word of it is doing something. The whole Bible, which means the discipline is answerable to texts it would rather not have. On a subject, which means it organises by topic rather than by the order of the books. Arranges, which means it produces something the Bible does not itself produce, a claim with a shape. And so a believer can act on it, which means the work is not finished when the account is accurate; it is finished when someone can use it.

You met the first comparison in the Hermeneutics track, at the fourth lesson of its fourth module, where systematic theology was set against biblical theology and each was shown guarding the other against a characteristic failure. That argument is not repeated here. Take it as read: biblical theology follows the historical order and asks what this writer said in his own idiom at his own point in the story; systematic theology follows a logical order and asks what is therefore true. If you cannot restate that distinction and name the failure each discipline invites, go back and read that lesson before this module goes any further, because this whole track is the second of those two jobs and you need to know what it is liable to do to you.

Two further neighbours were not covered there. Historical theology asks what the church has in fact taught, when, under what pressure, and with what dissent. It is descriptive, not prescriptive: its job is to report that the doctrine of purgatory has a datable development, that Augustine's views on grace hardened in the Pelagian controversy, that the Reformed and the Lutherans divided over the Supper at Marburg in 1529 and did not close the gap. Jaroslav Pelikan's five-volume The Christian Tradition, published between 1971 and 1989, is the standard modern example in English, and his own formula for why the discipline matters is worth carrying: tradition is the living faith of the dead, traditionalism is the dead faith of the living. A systematic theology written without historical theology will keep rediscovering positions the church has already tried and abandoned, usually without knowing why they were abandoned.

Practical theology asks how the church actually does what it is for: preaching, worship, pastoral care, mission, counselling, the shape of a service, the training of leaders. It is sometimes treated as the place where the real theology gets applied, which is a condescension the discipline does not deserve. What a congregation sings is a theology, and a funeral is a course in eschatology whether or not anybody planned it that way. Practical theology is where a doctrine is tested by whether it can be preached to people in trouble, and doctrines have failed that test and been revised because of it.

Three more terms will appear and are worth fixing now. Dogmatics is a near-synonym for systematic theology, more common in continental and Reformed usage, and it carries the added sense of working within a confessing community whose dogmas are given. Philosophical theology works on the conceptual questions doctrine raises, such as what it means for a timeless God to act at a moment, and it reasons more than it exegetes. Moral theology, or Christian ethics, takes the doctrine and asks what must be done. The boundaries between all of these are conventional rather than natural, drawn differently in different faculties, and nothing important turns on defending them.

Open any systematic theology and you will find roughly the same list of chapters: prolegomena, scripture, God, creation, humanity and sin, Christ, the Spirit, salvation, the church, last things. That list looks like the structure of the subject itself. It is not. It is an inheritance with a history, and knowing the history is the first defence against mistaking somebody's filing system for revelation.

The earliest attempt at a connected account is Origen's On First Principles, written at Alexandria in the two-twenties, which moves from God and the rational creatures to the world, free will and scripture. In the East, John of Damascus assembled An Exact Exposition of the Orthodox Faith in the eighth century, a hundred short chapters gathering the settled patristic teaching, and it remained the standard reference in Greek theology for centuries. In the Latin West the decisive book was Peter Lombard's Four Books of Sentences, compiled around the middle of the twelfth century: book one on God and the Trinity, book two on creation and sin, book three on the incarnation and the virtues, book four on the sacraments and the last things. For four hundred years, lecturing on the Sentences was how a man became a master of theology in a European university. Nearly every great medieval theologian wrote a commentary on it, Aquinas and Bonaventure and Scotus and Ockham among them. That is how a set of headings becomes invisible: it stops being one arrangement and becomes the shape of the room.

Thomas Aquinas broke the shape deliberately. The Summa Theologiae, left unfinished at his death in 1274, is ordered on a movement out from God and back to God: the first part on God and creation, the second on the human being's return to God through action and virtue and law and grace, the third on Christ and the sacraments as the way by which that return is made. The arrangement is itself an argument, that everything in theology is either God, or creatures coming from God, or Christ the road back. Notice what that does to Christology: it arrives late, not because Christ matters less, but because in this scheme he is the way rather than the destination. A different scheme would have produced a different emphasis, and Aquinas knew it.

The word loci comes into Protestant theology from rhetoric. In classical and Renaissance practice, loci communes, commonplaces, were the standard headings under which a student gathered material for argument, and Philip Melanchthon, who was a humanist teacher of Greek before he was a theologian, borrowed the technique. His Loci Communes Theologici of 1521 grew out of lectures on Romans and is usually called the first Protestant systematic theology. What makes it the best possible illustration of this section's point is what he left out. In the 1521 edition he declined to treat the Trinity and the modes of the incarnation, on the ground that such mysteries are to be adored rather than investigated, and wrote instead that to know Christ is to know his benefits. He added those doctrines back in the revised editions of the fifteen-thirties and forties. The same man, the same subject, and a decision about headings that changed what the book taught and then changed back.

After that the tradition settles and hardens. Calvin's Institutes began in 1536 as six chapters following the catechism, the law, the creed, the Lord's Prayer and the sacraments, and reached its final form in 1559 as four books following the Apostles' Creed: God the Creator, God the Redeemer, the way we receive the grace of Christ, and the outward means. The Protestant scholastics built enormous ordered systems, Johann Gerhard's Loci Theologici on the Lutheran side and Francis Turretin's Institutes of Elenctic Theology on the Reformed, arranged as sequences of disputed questions. The tidy Greek-derived scheme most English textbooks now use, with its bibliology and anthropology and soteriology and eschatology, is largely a nineteenth-century tidying of that inheritance.

Two modern rearrangements show that the question is still live. Friedrich Schleiermacher, in The Christian Faith, reorganised dogmatics around the Christian community's consciousness of absolute dependence on God, and in that scheme the Trinity ends up in a brief concluding section rather than at the head of the work. Karl Barth, in the Church Dogmatics, made the Word of God the opening doctrine and moved election out of the decrees and into the doctrine of God, arguing that Jesus Christ is both the electing God and the elected man. Both men were doing what Aquinas and Melanchthon did: deciding what governs what. You do not have to agree with either to take the lesson, which is that no arrangement is neutral, and the first question to ask of any system, including the one this track will give you, is what it put first and what that decision cost.

The Hermeneutics track named the main cost and you should not need it twice: a system fixes the meaning of a term and then hears that fixed meaning everywhere, so that a writer's distinctive voice is flattened into the system's vocabulary. Faith in Hebrews 11 gets read as faith in Romans 4, Qoheleth becomes an error to be corrected before he can be heard, and James is reduced to a writer whose only job is not to contradict Paul. That is the flattening, and it is the reason this discipline needs the other one. Here are three further costs that the earlier lesson did not cover, because they belong to the machinery of arrangement itself rather than to the reading of any single text.

The first is the heading with too little text under it. Every system has chapters that scripture does not obviously supply, and the chapter has to be filled. Prolegomena, the section you are reading now, is the clearest case: there is no book of the Bible on theological method. So the material comes from somewhere else, from philosophy or from the last generation's controversies, and it arrives with less scrutiny than an exegetical claim would get. The same pressure produces the seventeenth-century arguments about the order of the divine decrees, where supralapsarians and infralapsarians disputed the sequence in which God's eternal purposes are logically arranged, a question that has almost no direct textual footing and that generated very confident literature anyway. Watch for headings whose content is mostly inference, and ask what the inference is standing on.

The second is the text with no heading. Material that does not fit the filing system quietly stops being used. The Song of Songs has no natural slot in the standard scheme and has been handled mostly by allegory, which is one reason its literal sense was neglected for centuries. Lamentations does not fit. Neither do the imprecatory psalms, which ask God to break the teeth of enemies, and which most systematic theologies mention only as a problem. This is a real cost and it is measurable: take any system and ask which books of the Bible it never quotes. A discipline that claims to say what the whole Bible teaches can be caught out by that question more easily than it likes.

The third is the question whose form dictates its answer. Ask whether regeneration precedes faith or follows it and you will get an answer, and the answer will divide the Reformed from the Arminians, and both sides will cite texts. But the New Testament never puts the question in that form, and the shape of the question, a sequence of two instants, is imported. This does not mean the question is illegitimate; theology has to answer questions scripture did not anticipate, and refusing to do so is its own failure. It means that when the answer to a question feels forced, the first thing to examine is whether the question smuggled in a picture. Aquinas had a version of this discipline: he stated the objections to his own position first and at their strongest, and a reader who never states the objection in a form its holders would accept has not yet done the work.

The discipline has developed its own remedies, and they are worth naming because they are what this track will try to do. Exegesis first and arrangement second, so that a passage is heard before it is filed. Named texts under every claim, so that a position can be checked rather than merely accepted. The honest naming of what a position costs, since every position in a contested area costs something and the ones that seem to cost nothing are usually the ones whose bills have been hidden. And the practice of asking, of your own system, which of its conclusions you would least like to be wrong about, since that is usually where you have been least willing to look.

You already have a systematic theology. The Hermeneutics track made this argument about commands and you will recognise the move: every reader already sorts, and the only question is whether the rule is one you can state. The same is true of doctrine. Anyone who has believed anything for a year has an account of who God is, what went wrong, what Christ did about it and what happens at the end. It is rarely written down and almost never examined, which is precisely what makes it powerful.

What the earlier lesson did not do is show you where the unexamined system comes from, so do that now. It comes from hymns, which are the most effective doctrinal instruction most congregations receive, and which are not always careful. It comes from funerals, where a grieving family is told something about the dead that nobody wrote down beforehand and that will be believed for thirty years. It comes from the accumulated sediment of half-remembered sermons, from the theology of whichever film last made you cry, and from the sentences people say in a hospital corridor because silence is unbearable. Test it on yourself with the three sentences you wrote in the inquiry: you had an eschatology ready, you produced it in under a minute, and some of it had no text behind it at all.

This is why the church invented catechesis rather than leaving people to assemble a faith from whatever was lying around. Cyril of Jerusalem's lectures to candidates for baptism in the fourth century, the Heidelberg Catechism of 1563, Luther's Small Catechism of 1529, the Westminster Shorter Catechism of 1647, the Catechism of the Catholic Church of 1992 and the Orthodox tradition of catechetical instruction before chrismation are all doing one thing: making the system explicit so it can be inspected, corrected and handed on. Whatever you think of any particular catechism, the instinct behind all of them is sound and the alternative is not neutrality.

So the choice is not between having a system and reading the Bible plainly. It is between a system you can state and defend and one that runs you without your consent. An unstated system is not smaller than a stated one; it is the same size and less accountable, because you cannot notice a text telling against a position you have never put into words. The practical test is simple and uncomfortable: pick any doctrine you hold firmly and try to write the three passages it stands on and the one passage that gives it the most trouble. If the second half of that exercise comes up empty, the position is probably inherited rather than held.

The rest of this track is arranged under the standard headings, for the plain reason that they are the ones the literature uses and you need to be able to read the literature. You now know that the arrangement is a convention with a history, so use it and do not venerate it.

Every doctrine will be argued from texts, quoted rather than gestured at, and every position that serious Christians hold will be given in the form its own defenders would accept. Where the church is genuinely divided, this course will say so and will not manufacture a consensus. Where something is settled, it will say that too, because a teacher who treats everything as open is no more honest than one who treats everything as closed.

One habit to start now. When you meet a position in this track, ask three questions of it before you agree or disagree: which texts is it standing on, what does it cost, and who holds the opposite and why. A student who can answer those three about a view he rejects is doing theology. A student who can only answer them about the view he already held is doing something else.