When we speak of the necessity of theology, we’re speaking of strictly the necessity of doing it in a certain way. Why systematize it? Why can’t we just learn the Bible and leave it at that? Why consult historic theology? Why use our reasoning capacities for philosophical insight? The need of theology isn’t that we need theology. This much is obvious. The necessity of theology is the focus upon specifically why we need to embark on such a task as understanding. Can’t the learned and the men and women who have devoted their lives to ministry do such things? Why does the laymen need to establish their own theology and opinion?
In one sense, everyone is a theologian. Therefore, everyone will study theology whether they like it or not. With that, we see that the people of God will either take hold of good theology, because they have a healthy relationship with Christ, or they will simply take other people’s words as authority, sloshing down any kind of doctrine that might appear before them. It is important to exercise theological discussion among all the brethren, because without every person digging in, we will be left with a mass of people who say they believe, but don’t even know in what they believe.
In another sense, the necessity of theology is one of response. Peter tells us to always be ready to give a response to those who might ask reason for the hope within us. Do we take that as the mandate to the pastor, but we just work an office job? Or, is that something that Peter tells everyone, and so the nonbeliever in the office with us needs to also hear the Gospel? There are many who are asking questions. It is high time that we begin to give answers. Some of the questions are layered with years of doubt and bitterness. Others are genuine. In all cases, if we cannot give reason for why we believe, then why believe at all? This is not a “faith versus science” thing.
More specifically, why do we need to practice a systematic theology? One reason is that it is generally in human nature. We systematize for easy memorization and teaching. Not only do we desire a system for the basis of teaching and memory, but even, maybe especially, for an epistemological foundation for life. We all have the filter by which we view all things. If that filter is to be the Scripture, then we need to know what the Scripture says. There are two ways in doing this: memorize the whole Bible or systematize what it teaches into general categories. We can argue about semantics, but what no true believer will argue is the doctrine of the trinity, the Lordship of Jesus, the incarnation, the virgin birth, etc. There are core doctrines of the faith that we all hold to, and we need to understand and appreciate what they are and how they relate to the rest of life. Without both the systematic theology and practical theology walking hand-in-hand together, we are left to guesses about how any of this relates to anyone.
Another reason, which goes right along with the previous reason, is that Christianity must be defined in a coherent system to be understood and defended. We believe in the one true God. That’s great, and it can be a direct quote of Scripture, but realize that this statement is in itself a systematic theology. We then further dissect the statement, adding more detail and subtracting implications that we don’t hold to, until we finally get an articulate and definitive statement.
Another couple reasons for systematic theology is that it aids in memorization and learning of Scripture, and it enables spiritual growth. While I don’t entirely disagree with these, I also don’t emphasize them. I think there are other ways in memorizing Scripture, and for that reason systematic theology is not necessary to memorize it. Also, I believe that spiritual growth is an act of God, and not simply our “systematic theology”. Once again, while it can invariably lead to spiritual growth, one man plants, the other waters, but only God makes things grow. Likewise, repentance plants, prayer and study of Scripture waters, but only God makes things grow. We shouldn’t idolize our theology.