Christian theology is an outline of the truth revealed by God in Holy Scripture, which points us to the Persons and work of the Godhead.


Christian theology is not human speculation about the supernatural (as ancient Greek mythology was), but is the product of Christians needing to explain how God can be three Persons in one and how the second of these Persons could become a man without ceasing to be God. As such, Christian theology is primarily about God, but the word commonly includes the study of all truth revealed in Scripture. While humans are able to know some things about God through contemplating his works in creation, unaided by any special divine revelation, it is necessary for God to have revealed himself personally to us as the triune God of our redemption. We know this God today through his scriptural revelation, which is the only reliable and detailed source for our knowledge of God. Christian theology is therefore best understood as an outline of the truth revealed in Scripture that points us to the Persons and work of God.

“Theology” is a word of Greek origin that means “the study of God.” It was first used by Plato (fourth-century BC) with reference to the pagan Greek gods, corresponding to what we would now call “mythology.” Plato believed that it was irrational nonsense and wanted to ban it from his ideal state. This would have little relevance today except for the fact that a number of modern atheists have accepted Plato’s definition and applied it to Christian theology, which they treat as nonsense for the same reason. What they fail to understand is that Christian theology is not human speculation about the supernatural but the analysis of a divine revelation contained in the Bible. Critics may doubt the authenticity of that revelation, but Christian theologians work with objective source material and do not speculate at random in the way that the ancient Greeks did.

Theology, as an academic discipline, is not revealed or commanded in the Bible itself, nor is it a major feature of other Biblically-based monotheisms. Jews, for example, have never developed it in the way that Christians have done, and to the extent that modern Judaism has a theology it is largely the result of Christian influence. Muslims are in a similar position. They possess a revelation in the form of the Qur’an but do not have a developed theology in the Christian sense. As with Judaism, Islamic theology, such as it is, is largely an attempt to explain their beliefs to people who think in a basically Christian way. Jews and Muslims both believe that God is essentially unknowable and that theology, in the strict sense, is therefore impossible. Instead of that, they have both developed extensive legal traditions which analyze and apply their revelations in a way that corresponds to Christian theology. For that reason, they are sometimes regarded as theological, especially by observers used to the Christian approach.

Christianity stands apart from its related monotheisms because it confesses that God is a Trinity of Persons, one of whom became a man in Jesus Christ. To both Jews and Muslims this is unacceptable to the point of being blasphemous, but for Christians it is fundamental. Christian theology is the product of the need to explain how God can be three Persons in one and how the second of these Persons could become a man without ceasing to be God.

The question is further complicated because in popular usage, the word “theology” is often expanded to include a number of other things that are not directly connected with the being of God. These include the creation and fall of mankind, the way of salvation, the nature of the church and the consummation of all things at the end of time. It can be argued that these subjects are all covered by the Biblical revelation and must therefore be studied in the context of Christian theology, but they are secondary to the doctrine of God and not strictly theological themselves.

This double meaning of the term “theology” is at least partly the result of a conceptual shift that occurred in the late sixteenth century, as the Protestant Reformation took root. Until that time, the doctrine of God had always come first and was then followed by the doctrine of revelation and its contents. But beginning with the Second Helvetic Confession of 1566, the Bible was placed at the beginning of the church’s confession of faith, with everything else, including the doctrine of God, being treated in light of that. As a result, modern Christian theology is usually not so much the study of God as an analysis of his revelation. Given that our knowledge of God comes mainly (if not entirely) from that revelation, this makes logical sense from an academic point of view, though it is historically inaccurate. In the history of the covenant as recorded in the Bible, knowledge of God preceded the writing of Scripture by several centuries and the Biblical record bears witness to what was originally an oral communication from him to (and through) the Old Testament prophets, the New Testament apostles and above all Jesus Christ.

The Sources of Theology

All theology derives ultimately from God and his self-revelation. This is inevitable, because God is the source of all things and his creatures can only study him to the extent that he allows them to do so. The Bible tells us that God created human beings in his image and likeness (Gen. 1:26–27), which has often been understood to mean that we can communicate with God and understand him when he speaks to us. From the beginning, God spoke to his human creatures and they had at least some knowledge of him. How much of this was communicated directly by him and how much was deduced by humans from their circumstances in difficult to say and has been the object of considerable controversy.

If human beings were placed on earth in order to govern it as God’s representatives, it stands to reason that they must have possessed some innate understanding of what they were supposed to be doing, which must have entailed at least a partial knowledge of the mind of God. In later times, this appeared in the form of so-called “natural theology,” which is the belief that human reason, unaided by any special divine revelation, is capable of finding God by contemplating his works in creation. The near universal existence of religious beliefs in human culture has often been cited as evidence for this, and there may be some truth in it. The Bible tells us that “the heavens declare the glory of God” (Ps. 19:1), and when Paul spoke to the Athenians he quoted pagan poets in support of his claim that they were aware of him (Acts 17:28).

The difficulty with natural theology is that while it may be able to convince us that there is a moving power behind the universe, it cannot describe what that power is like. We can deduce from our reasoning that the world must have come from somewhere and that the order we see in it cannot be accidental, but we cannot go much further than that. The classic analogy of the watch and the watchmaker illustrates the problem quite well. We can tell that a watch is too complicated to have come into existence by itself and that it must have a maker. But the watch does not reveal who the maker is, what he is like, or why he made the watch. In other words, natural theology can help us ask the right questions but it cannot provide us with solid answers. Just as we can only know the watchmaker if he reveals himself to us, so we can only know the power behind the universe if he tells us who he is. Even then, this does not necessarily amount to proof that he is who he claims to be. We have to trust that the watchmaker is telling us the truth, just as we have to trust that the God who has revealed himself to us is who he says he is.

Here we enter the realm of faith, which is trust in the one who has told us that he is our Creator, Redeemer, and Lord. How has he done this? According to the Bible, God first revealed himself to the world through personal encounters with men like Noah, Abraham, Isaac, and Jacob. We do not have direct access to those encounters but are dependent on accounts of them that were written several centuries after they occurred. We believe they are accurate in what they tell us, but it is reasonable to suppose that they do not tell us everything that transpired at the time. What has been transmitted to us is the essential core of the relationship that God established with those ancient patriarchs. It comes to us in the form of a covenant, which is a series of principles and promises on which our relationship to God is based. The truth of this covenant is tested by the experience of each generation. We believe that the God who spoke to Abraham continues to speak to us today and to fulfil the promises that he made to the Israelites so long ago, and we look to our experience as evidence for the truth of this claim. By this means we come to appreciate something of the character of God, who is revealed to us as being both eternal and faithful. Because he is eternal, he does not change, and his divine nature is above and beyond the limitations of the world he has made. Because he is faithful, he reveals himself as a God of relationships that are ordered and governed by love. His human creatures have done nothing to deserve divine favor—on the contrary, they have done everything to reject it by sinning against him. But God cannot deny himself, and so he continues to love us, even to the point of sending his Son into the world in order to pay the price of our disobedience to restore us to his fellowship.

This restoration occurred in the life, death and resurrection of Jesus Christ, the man who was the incarnate Son of God. Jesus Christ is the ultimate source of Christian theology, which is shaped and ordered by his teaching. It was Jesus who revealed the inner life of God as that of a Trinity of divine Persons. It was Jesus who interpreted the meaning of the revelations given before his time, and who fulfilled them by his atoning sacrifice on the cross. Finally, it was Jesus who told his followers what the future would bring, and how both our life and that of the world would come to an end. This teaching was entrusted to his disciples, who became the apostles of the Christian church and whose message forms the basis of our confession of faith today.

It is in this context that the role of the Bible must be explained. Both the covenant and the relationship with God that it entailed existed long before there was any written record of them, and so the Bible is first and foremost a witness to a reality that lies beyond and is bigger that it is. But at the same time, it is the indispensable account of that reality, and without it we would have no knowledge of God or of his plan for the salvation of mankind. It is not a complete transcript of everything that God has ever said or done and does not claim to be. On the contrary, John the Evangelist tells us that it is a digest of God’s actions in and through Jesus Christ, a digest that is necessary because the whole story is too big for us to comprehend (John 21:25). What we have, therefore, is not the whole truth, but an accurate and definitive guide to what we need to know for our relationship with God to function in a meaningful way. The Bible points us in the right direction and it will not lead us astray—as Paul said, the (written) Law is a schoolmaster that points us to Christ (Gal, 3:24). We do not worship it but the one who gave it to us.

In this respect, the Bible is a picture of what Christian theology is and does. Theology is the study of God, but it is not a substitute for the personal relationship with him that it describes. We see the importance of this distinction in the conversion story of Saul of Tarsus, the man who is better known to us as the Apostle Paul (Acts 9). Saul knew his Bible and was convinced that he understood its meaning. That is what led him to persecute Christians, because he thought that they had misinterpreted the Law of God and were leading people astray as a result. But then Saul had a personal encounter with Jesus Christ and his life was changed. That encounter was essential, but it was not self-explanatory. Saul did not immediately get up and start preaching the message of salvation in Christ; instead, he was taken to the home of Ananias in Damascus and instructed by him in the meaning of what had occurred.

The story of Saul’s conversion does not explicitly state that Ananias explained the true meaning of the Hebrew Bible, but that is implied by the narrative and is confirmed by what we know happened in other cases. For example, the men on the road to Emmaus were met by Jesus, who remained anonymous even as he expounded the Scriptures to them. It was only when he revealed himself to them that they understood what had happened, but there was no doubt in their minds as to the source of their enlightenment. “Did not our hearts burn within us while he talked to us on the road, while he opened to us the Scriptures” (Luke 24:32)? Opening the Scriptures was what Paul spent the rest of his life doing because it was in them that the secret of eternal life was to be found, the revelation of salvation in and by Jesus Christ.

This is what true theology is. It is not speculation about the meaning of the universe, which is an activity left to the philosophers and regarded with some suspicion in the Bible (1 Cor. 2:6–13). Rather, it is expounding the contents and meaning of the Bible, which is the only reliable and detailed source for our knowledge of God.

This principle must be borne in mind because the Church has often gone astray and been divided when it has forgotten the limitations within which theologians have to work. The extension of “theology” to cover every aspect of the Christian life has led to problems when theologians have definitively spoken on matters that are unclear or omitted from the Scriptural text.

Christian theology is therefore best understood as an outline of the truth revealed in Scripture that points us to the Persons and work of God. It may be supplemented to some extent by things like personal experience or Church tradition, but these secondary witnesses are subject to the test of compatibility with the Biblical revelation, and if they fail that test, they must not be insisted upon. Our knowledge of God may not be confined to the teaching of the Bible, but it is defined by it, and in this way theology helps us to understand our relationship with God and to interpret it correctly within the communion of saints that is the Church.

Further Reading

This essay is part of the Concise Theology series. All views expressed in this essay are those of the author. This essay is freely available under Creative Commons License with Attribution-ShareAlike, allowing users to share it in other mediums/formats and adapt/translate the content as long as an attribution link, indication of changes, and the same Creative Commons License applies to that material. If you are interested in translating our content or are interested in joining our community of translators, please reach out to us.

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