“Before we can organize Christian theology into a coherent body of doctrine, we need to look at it according to its biblical parts, as well as the biblical books that make up those parts. For example, if we want to seek to gain a proper understanding of the kingdom of God, using both the Old Testament and New Testament contributions, we must first look at what various biblical books tell us about it.”
Prior to the Protestant Reformation, theological reflection was generally in the realm of what we would today call systematic theology. As can be seen by its name, the goal is to systematize or order the teaching of the Bible into a coherent expression of doctrine. One expression of this is in those rather large theology texts that seek to explain the Christian faith in a comprehensive fashion, covering its content under the standard doctrinal headings. But systematic theology can also be less broad and concern itself with looking at a particular doctrine, such as redemption. Systematic theology begins by observing what both the Old and New Testaments teach about it, with the aim of organizing all that material into a thorough and orderly explanation of the topic.
Biblical theology, however, is defined differently. With the Protestant Reformation came more of a distinction between biblical and systematic theology. Before we can organize Christian theology into a coherent body of doctrine, we need to look at it according to its biblical parts, as well as the biblical books that make up those parts. For example, if we want to seek to gain a proper understanding of the kingdom of God, using both the Old Testament and New Testament contributions, we must first look at what various biblical books tell us about it. So what do we learn about the kingdom of God from books such as I and II Samuel? Isaiah? Matthew, Mark, and Luke?