1. Systematic theology exists because the God who knows and loves himself in the bliss of the Trinity is pleased to make himself an object of creaturely knowledge and love through holy Scripture.
Theology in its essence is “wisdom”—a knowledge that is ordered to love (practical wisdom), and a love that rests in knowledge (contemplative wisdom). More specifically, theology is wisdom about God and all things in relation to God.
This wisdom exists first and foremost in God: God knows and loves himself in the bliss of his triune life as Father, Son, and Holy Spirit (Matt. 11:27; 1 Cor. 2:10–11). This wisdom exists secondarily and derivatively in creatures because God is pleased to make us happy by making us friends in the knowledge and love of himself (John 10:14–15; 15:15; 17:3; 1 Cor. 2:12).
Though not the only source for the knowledge and love of God (see Psalm 19; Rom 1-2), holy Scripture is the supreme source for the knowledge and love of God in this life (see 2 Peter 1:16–21). Therefore holy Scripture is the supreme source and norm for the “systematic” study of theology.
2. Systematic theology is a way of studying the Bible that attends to the full scope of biblical teaching.
As a discipline devoted to studying and teaching holy Scripture, systematic theology seeks to give heed to the full scope of biblical teaching. Systematic theology does not content itself to focus upon a single biblical author—say, Isaiah or Paul—or a single biblical theme—say, the doctrine of justification. Systematic theology is a discipline that devotes itself to “the whole counsel of God” (Acts 20:27).
The only way the church truly submits to the Bible’s doctrinal and moral teaching is by submitting to the full scope of the Bible’s doctrinal and moral teaching. Failure to attend to the whole counsel of God “leads to one-sidedness and error in theology and pathology in the religious life” (Herman Bavinck).
3. Systematic theology is a way of studying the Bible that attends to the unity of biblical teaching.
Because God is the primary author of holy Scripture (2 Tim. 3:16), and because God is a God of truth (Titus 1:2), systematic theology seeks to discern the unity, harmony, and beauty of biblical teaching. Systematic theology seeks to coordinate the teaching of various biblical authors across various redemptive-historical epochs and literary genres, and across the Bible’s two testaments, in a way that does not mute or flatten the diversity of biblical teaching but allows it to shine forth in its multisplendored richness.
Furthermore, systematic theology seeks to coordinate the teaching of holy Scripture with that which may be learned outside of holy Scripture through general revelation, recognizing that, because the Bible is the supreme source of wisdom about God, it plays the role of adjudicator and judge in relation to all lesser sources of wisdom about God.
4. Systematic theology is a way of studying the Bible that attends to the proportions of biblical teaching.
While systematic theology is a “comprehensive science,” treating God and all things in relation to God, John Webster reminds us that systematic theology is not “a science of everything about everything.” The Bible emphasizes certain things and says very little about other things. The Bible has matters of “first importance” (1 Cor. 15:3) and matters of secondary importance (Matt. 23:23).
Systematic theology cannot afford to neglect matters of primary or secondary importance (Matt. 23:23). But it must seek to reflect the Bible’s own emphases and priorities in its attention to and presentation of biblical teaching.
5. Systematic theology is a way of studying the Bible that attends to the relationships of biblical teaching.
Systematic theology’s concern with the Bible’s doctrinal and moral teaching includes a concern to grasp the connections or relationships between the Bible’s various doctrinal and moral teachings. Systematic theology seeks not only to understand what the Bible says about “salvation” or “good works.” It also seeks to understand the relationship between “salvation” and “good works” (Eph. 2:8–10). Confusion about the relationships between various doctrines inevitably leads to confusion about the doctrines themselves. The supreme relationship that systematic theology considers is the relationship between God and everything else.
God’s theology—his wisdom regarding himself and all things in relation to himself—is simple and eternal.
6. A well-ordered system of theology is governed, primarily, by a God-centered organizing principle.
The doctrine of God is the primary doctrine to which systematic theology devotes its attention and to which systematic theology seeks to relate all other doctrines. Systematic theology is God-centered biblical interpretation.
Systematic theology, in this regard, adopts a disciplinary protocol that corresponds to the nature of reality: “all things,” the Apostle Paul instructs us, are “from him and through him and to him” (Rom. 11:36). Systematic theology does not pretend to grasp anything unless it can grasp it in relation to God as Alpha and Omega.
The doctrine of God is therefore not simply the first doctrine in a series of doctrines in systematic theology. The doctrine of God directly informs every topic within a well-ordered system of theology. There is a sense in which every doctrine in systematic theology is part of the doctrine of God. Systematic theology is not so much about creation, providence, salvation, and consummation as it is about God creating, God providentially governing, God saving, and God consummating creation to be the temple of his triune glory. Systematic theology “describes for us God, always God, from beginning to end—God in his being, God in his creation, God against sin, God in Christ, God breaking down all resistance through the Holy Spirit and guiding the whole of creation back to the objective he decreed for it: the glory of his name” (Herman Bavinck).
7. A well-ordered system of theology is governed, secondarily, by a historical or dramatic organizing principle.
Because systematic theology is concerned with God, it is also concerned with the works of God. “Great are the works of the Lord, studied by all who delight in them” (Ps. 111:2). Systematic theology follows the course of God’s works from his creation of all things out of nothing, through his providential government and care of all things, to his redemption and perfection of creation through the incarnation of the Son and the outpouring of the Spirit.
In its task of tracing the course of God’s works in nature, grace, and glory, systematic theology follows a historical or dramatic organizing principle. Within a well-ordered system of theology, each doctrine is not only traced to God as its author and end. Each doctrine is also coordinated with other doctrines on a dramatic-historical axis from creation to the consummation of the kingdom of God. Systematic theology is God-centered, redemptive-historical biblical interpretation.
8. Systematic theology’s necessary interest in historical theology is more than mere historical interest.
God’s theology—his wisdom regarding himself and all things in relation to himself—is simple and eternal. Our theology—our wisdom regarding God and all things in relation to God—is social and historical. One generation commends God’s works to another, and declares his mighty acts (Ps. 145:4).
For this reason, systematic theology has a necessary interest in historical theology, the study of theology as taught and transmitted through time. Systematic theology cares about the early fathers of the church and the creeds which are the fruit of their ecclesiastical labors. Systematic theology cares about the medieval doctors of the church and the various ways in which by faith they sought to understand the mysteries that God has revealed in his Word. Systematic theology cares about the Protestant Reformation and its confessions and about Protestant orthodoxy and its magnificent systems of doctrinal and moral theology. And systematic theology cares about the Enlightenment and its aftermath, with which it is still coming to grips.
In each instance, systematic theology’s interest in historical theology is not merely a matter of historical interest. Systematic theology’s task is primarily prescriptive rather than descriptive. It is concerned with teaching what the church must believe and do, not simply what the church has believed and done. However, because the church is a social and historical reality, and because the history of theology is also the history of biblical interpretation (Gerhard Ebeling), systematic theology cannot teach what the church must believe and do unless it attends to what the church has believed and done.
The church cannot know what it must confess in our day and age on the basis of holy Scripture unless it knows what the church has confessed in other days and other ages on the basis of holy Scripture.
9. Systematic theology serves practical ends.
The systematic study of God and God’s works as revealed in holy Scripture serves a number of practical ends. By providing a summary form of scriptural teaching, systematic theology makes us better readers of holy Scripture (recall John Calvin’s stated purpose in writing his Institutes of the Christian Religion).
Furthermore, by teaching us to contemplate God and all things in relation to God, systematic theology furnishes the Christian mind with principles for action. Systematic theology informs our faith, teaching us to apprehend God and all things as they really are and to receive all things as gifts from God’s fatherly hand. Systematic theology informs our hope, teaching us to anticipate the fulfillment of God’s eternal kingdom in accordance with God’s promise. And systematic theology informs our love: directing faith and hope to their object in God, we find a light to navigate our path out of the misery of Adam’s race into the bliss of Jesus’s eternal kingdom and to awaken fitting forms of devotion, adoration, and admiration for God, neighbor, and world.
10. Systematic theology also serves contemplative ends and thereby prepares us for our chief end, which is to glorify God and enjoy him forever.
Though systematic theology serves a number of practical ends, systematic theology’s ends are not exclusively practical. Systematic theology also serves contemplative ends.
As a species of practical wisdom, systematic theology directs love to prudential action in the world. As a species of contemplative wisdom, systematic theology directs love to its supreme and final resting place in the knowledge of God: “This is eternal life, that they may know you, the only true God, and Jesus Christ whom you have sent” (John 17:3). By teaching us to contemplate God and all things in relation to God, systematic theology teaches us to trace all things from, through, and to God, enabling us to give him all the glory (Rom. 11:36), and it directs us to the one in whom alone our thirst for happiness is quenched (Ps. 42:1–2; John 6:35). Systematic theology thus assists us in realizing the chief end of man, which is to glorify God and enjoy him forever.
Source: 10 Things You Should Know about Systematic Theology
The ESV Study Bible
The ESV Systematic Theology Study Bible
Systematic Theology: An Introduction to Biblical Doctrine by Wayne Grudem
God Is Love: A Biblical and Systematic Theology by Gerald Bray
Everyone's a Theologian: An Introduction to Systematic Theology by R.C. Sproul
Systematic Theology: An Introduction to Christian Belief by John Frame