There are a lot of parts to theology, and although over-specialization is always bad, some division of labor makes a lot of sense unless you’re personally interested in earning degrees in everything from Hittite to Herodias to Haplography to Heidegger’s Hermeneutics of Hegel’s Historicism. Here’s how I see the labor divided.
While the various theological disciplines are peers, each operating with their own independent and valid methodologies, there is also a kind of normative order to them which is dictated by the one object which they study in common. Because Christianity is based on scriptural revelation, the biblical disciplines have a decisive priority when it comes to engaging the content of the faith. As Scripture is absolutely primary, the disciplines which engage it directly are at the front of the line: exegesis and the field which calls itself biblical theology.
As contemporary thinkers undertake the task of interpreting Scripture, historical theology steps next into line, because it will not do to pretend that these texts and concepts have not had a history of effects in the interval between their time and ours. Christian theology is a long conversation with Scripture, and historical theology attends to the earlier voices in the conversation.
Philosophical theology, understood modestly as the discipline that ensures terms are being used clearly, unambiguously, and consistently, is involved all along the way, but becomes especially prominent after the biblical and historical scholars have given their account of what Scripture says and what the Christian tradition has thought it says. There is a more robust kind of philosophical theology which does not just clarify terms but also has metaphysical and epistemological commitments which it seeks to coordinate with the revealed truth of Scripture.
This kind of philosophical theology shares space (and sometimes grrr disputes turf) with the discipline of systematic theology, whose task is to synthesize exegetical, biblical, and historical theology in order to re-state it in contemporary terms. Biblical and historical theologies can limit their projects to careful descriptive work in a historical past tense, but at the level of systematic theology, truth claims must be phrased in the present tense.
Last in line, logically speaking, are a host of practical disciplines such as ethics, homiletics, counseling, Christian education, spiritual formation, and apologetics. These fields begin their work in a receptive mode, taking theological truth and applying it to current events, the life of the church, and actual people.
This schematic account of the order of the theological disciplines is a sketch which could probably start a real faculty brawl at most good schools of theology. While it is not quite fair to the boundaries of any of the disciplines, it serves as a good first statement of the chain of command among the disciplines.
I say â€œfirst statementâ€ because as soon as all the fields are present and accounted for, the disciplines which are downstream, so to speak, begin to exert pressure on the disciplines which are upstream. Just because homiletics is toward the end of the line, for example, does not mean that it is merely passive in its reception of Christian thought. If a doctrine comes down the line which in the final analysis is simply unpreachable, it is a good sign that something has gone wrong upstream. A theology which gives rise to a spirituality which nobody can live out is a highly suspect theology, however good its biblical, traditional, and logical credentials may claim to be.
We cannot switch our doctrines to whatever happens to work, but we can take dysfunction as an indicator that our previous conclusions need to be revisited.
Such back-loops are in evidence everywhere in the theological disciplines. In fact, a lot of the most interesting work happens at the margins between disciplines, and at the pressure points where back-loops make re-thinking necessary. For this reason, it’s just as important for theologians to dabble in each othersâ€™ fields as it is for them to respect the boundary markers and dig deep in their own fields.
A final plug for systematic theology, which is my own field and therefore, in my humble opinion, clearly THE MOST AWESOMEST OF ALL THE THEOLOGICAL FIELDS. A terrain as heavily traveled and cross-tracked as theology could use a traffic cop. Somebody’s got to help manage all those intersections and border crossings so there are a minimal number of interdisciplinary doctrinal fender benders. That traffic control agent is also going to need to know enough about each discipline to be able to communicate with practitioners from each of them, and translate their arguments into the language and methodology of the other disciplines. That task falls to systematic theology, and constitutes a pretty big chunk of its work.
Another observation: Some theological subjects are so huge that they cannot be adequately handled by any of the disciplines. These subjects require a concerted effort from the entire theological faculty, with each doing their part to investigate the reality in question. My favorite example of this is the doctrine of the Trinity, and that too is a special concern of the systmatic theologian.