The first seminary class I ever took was THEO 5301: Systematic Theology 2. I’m not sure why I started with the second survey class, but the professor began the lecture by covering the basics. In the first lecture, the professor taught me something so foundational to theology that it changed the way that I understand the entire field. By grasping this one idea, he brought my understanding of theology to an entirely new level. If all Christians grasped this idea, it would change the way that they think about God and the Bible.
In the first class, the professor said that Christian theology usually covers a handful of topics. Christians have specific beliefs about how God reveals himself to us, who God is, who Jesus is and what he does, who the Holy Spirit is and what he does, who we are, how we can receive salvation, what the church is and does, and how the world will end. Though that’s not exhaustive, that’s a good starting point for understanding Christianity. Indeed, if you grasp this list, you’ll realize that most sermons, Bible studies, and Bible verses apply to one or two of these topics. When we grasp the significance of this list, we’re able to associate what the Bible says with things that we already know. This makes it much easier to learn from reading the Bible, listening to sermons, and reading books.
This method is not something new. As far back as the 16th century, theologians were creating similar thought systems to use in teaching the faith. Philip Melanchthon, Martin Luther’s disciple, wrote the Loci Communes, or the Common Places. In this book, he organized Christian theology according to the most important topics. He said this method of thinking would help those young in the faith in two ways. First, it would teach them to “know what they should especially look for in the Scriptures.” Second, this method would help them realize when a person made a theological error. This method is a time-tested system for remembering what the Bible teaches.
When I grasped the significance of this idea, it revolutionized the way I thought about my faith. When I read the Bible, I began to see how different verses teach us about different doctrines. When I wrote sermons, I began to understand that I needed to make sure to teach about all the different doctrines. When I disagreed with an idea, I saw more clearly why I disagreed with the idea. For a person who wants to learn about theology quickly, this method is invaluable. Indeed, upon grasping this system, most Christians would be surprised at how much theology they already know.
Notes & Sources
 Philip Melanchthon, Commonplaces: Loci Communes 1521, trans. Christian Preus (Saint Louis: Concordia Publishing House, 2014), 20.