Why is Theology important? We’ve established that theology concerns itself with speech about God, with the speech of God, and with the variety of experiences that are said to derive from Him. This is theology according to its most general definition. Rendered in this way, theological reflection would also include the psychology, sociology and philosophy of religion, as well as the study of any and all faiths and not just Christianity. For our purposes, however, we are here concerned with distinctively Christian theology. More specifically, we are concerned with Christian theology as an intellectual discipline of study.  We may engage in this discipline within the academy or the Church or on a purely private basis. Wherever we choose to encounter it, we should first pause to ask the question: why is it important to study Christian theology at all?
This question is not easily answered. After all, 'theology' has not always been the friend of faith. Theological study might be helpful for one person and completely destructive for another.  I’m aware that this is very real and, for some, rather intimidating. However, many would say from experience that theological study can be a force for good. What's more, it's becoming increasingly clear that greater theological literacy is necessary for those in the Church. Permit me, then, to suggest seven reasons why the study of Christian theology is so important.
First, Christian theology can be personally beneficial. It’s not necessarily true that the study of faith increases one’s own. But from my experience and that of many others, theological study often proves to be a source of many blessings. Not just because it paints a big picture that satisfies, but also because it girds you with rock-solid truths that comfort you when times are tough. When circumstances are less difficult, those same truths help to shape and crystallise your knowledge of God, leading you to a place of worship.  Second, Christian theology is pastorally helpful. In the same way that theological study can help you as an individual, it can also assist you in your helping of others. To know truth and to know truth well is to be able to 'administer' it when appropriate. Of course, it’s not the case that all theologians are good pastors. The study of theology will not necessarily transform you into a ‘people person’. (You’ll have to work on that separately, I’m afraid.) But it is true that we are called to console with the consolation we have ourselves received (2 Cor 1:3-4), to mourn with those who mourn (Rom 12:15), and to bear one another’s burdens (Gal 6:2). You can obviously do this without being a theologian. But being a theologian can help you understand the nature and order of a problem, primarily because theology helps to arrange human reality according to the reality of God. In a pastoral context, this is often greatly valuable..
Third, Christian theology is vital for the Church. As we established in the previous section, all of us are theologians. This is no less true of Churches in general. All expressions of Church assume theological distinctives, even those that don’t bother with being explicitly ‘theological’. Every decision made will beg a question of theology, even if the decisions are utterly mundane. For example, choosing to allow the non-baptised to take communion may or may not be ‘correct’, but it presumes something about the nature of the sacraments and the purpose of Church. Deciding to sing anything other than the Psalms may or may not be ‘right’, but it presumes something about what worship is and how we should use the Bible. Resolving to be an established Church with a formal connection to the State may or may not be ‘good’, but it presumes something about how we should understand politics and the Kingdom of God. These are just three examples, but they illustrate how the Church cannot divorce itself from theological reflection. Indeed, it is the Church’s job to do theology and theology should be, in its very essence, ecclesial. Fourth, Christian theology is publically confrontational. It is designed for challenge and conflict chiefly on account of theology’s subject matter – He who is Lord of Lords. To study theology is to study matters of the Kingdom of God and to come to terms with its authority over all other authorities. The theologian’s mandate is electrifyingly exciting. It is not simply to maintain consistency with regards preaching and practice; it’s much more than that. The theologian is tasked with informing the Church’s confession to society and government, offering a reminder of our accountability before a Holy God.  Christian theology has something vital to contribute not only to the academy and the Church, but also to society at large.
I'd hope that these reasons help illuminate why the study of Theology is so important. It's both pastorally and apologetically useful, and it can help inform the Church’s mission. More than this, it carries the exciting possibility of public engagement as well as the potential for personal blessing. This is not an insignificant enterprise, one that is well worth your time.
For Part  - Intro - see here.
For Part  - "Sources" - see here.
For Part  - "Types" - see here.
For Part  - "How?" - see here.
For the PostScript, see here.
 It is not exactly clear, however, what type of discipline theology is. As perplexing as it may be to us today, theology has historically been considered a science. (E.g. Aquinas, Summa Theologia 1.1.2; and Barth, Church Dogmatics §1.1.) Our difficulty in embracing theology as a ‘science’ likely stems from a relatively narrow understanding of what makes something ‘scientific’. We take the word to refer exclusively to the natural sciences, such as biology, chemistry and physics. The word, however, derives from the Latin term scientia, which simply means ‘knowledge’. Within this umbrella category we would include the natural sciences, but we may also include other critical disciplines whose objects of study include different realities of human existence. In German, these disciplines are referred to as Geisteswissenschaften – the ‘human sciences’. The study of history, language and philosophy would be counted as a ‘human science’, and so would theology. For more on this distinction, see the beginning of Macquarrie’s Principles of Christian Theology (1977, SCM Press).
 In his Little Exercise for Young Theologians (1962), Helmut Thielicke writes about this very problem. He gives the example of a faithful but theologically naïve medical student who suffers at the hands of two theologians whilst in a Bible study. Instead of aiding his understanding they harangue him and make him feel stupid. The medical student says of his encounter: “Although my fate and my life were at stake, those others came at me with their routine. I found in them no trace of life or truths learned by experience. I smelled only corpses of lifeless ideas. … I was looking for a Christian in whom I could detect a flame. I found only burnt out slag”.
 Many of the reasons I suggest here are pertinent to those who study theology with a Christian faith. Does this mean that the study of theology is unnecessary for those who do not believe? Not necessarily. A non-believer would want to study Christian theology to know what she does not believe. There is no virtue in disbelieving a caricature. One might also suggest that a secular intellectual should value and cherish truth, in whatever form. To study Christian theology with an aim to accumulate knowledge concerning its history, politics and phenomenology is to be applauded. At the very least, it is possible to study Christian theology hypothetically – using one’s imagination to put oneself in the place of a believer. (On this notion, see Brian Hebblethwaite’s The Problems of Theology .) It is therefore possible and desirable for a non-Christian to study Christian theology.
 This notion of Christian theology being publically confrontational is not at all novel. The first hearers of the Gospel were recorded as having noticed its counter-cultural and controversial message (e.g. Acts 17:6-7). The revolution of the Reformation was notable not only for its theological changes but also for its social and political dimensions (e.g. Calvin’s Institutes IV.XX). More recently, 20th Century theologians Karl Barth and Dietrich Bonhoeffer helped author the Barmen Declaration of 1934 – a confession that set itself against the Nazification of the German Church. Bonhoeffer himself was executed by the Nazis towards the end of the war, precisely on account of his theologically informed opposition to Hitler.