Deriving from two Greek words, theos (God) and logos (word or discourse), the term theology simply refers to the study of or discourse about God. For students of the Bible, theology is the product of Bible study. In other words, it is not something we should read into the Bible or even use as a grid for understanding the Bible. Instead, we should come to the Bible objectively, letting it say what it says. The resulting body of knowledge, derived solely from the text, we could call a Biblical theology.
A next and helpful step (after studying the Bible in context) is to systematize the teachings of the Bible, or to categorize them, so that we can understand all of what the Bible teaches on a particular topic. Systematization can help us to avoid making big assumptions about narrow contexts. The product of systematizing Biblical theology into categories is often referred to as systematic theology, and there are eleven basic categories of systematic theology representative of a truly Biblical theology. We need to understand the Biblical teaching on these eleven topics (even if their titles are artificial):
From the Greek biblios, bibliology is the study of the book, or more specifically, the study of the Bible. This topic deals with issues of definition, authority, and interpretive method. It is vital to have a solid bibliology, because if we don't approach the Bible properly, then we have no real authority to speak on any of the other areas of systematic theology. 2 Timothy 3:16-17 and 2 Peter 1:20-21 are good passages to study related to bibliology.
2. Theology Proper
The term proper is used in the sense of a proper noun, so theology proper refers to the study of the person of God. This study considers the person, and attributes and character of God. Oftentimes, this study will include discussion of the Father, Son, and Holy Spirit, though Son and Spirit are often considered as separate studies altogether. Issues like the holiness of God, and the doctrine of the trinity are considered in theology proper. Job 38-41, Isaiah 6, 40, and 48, and Revelation 4 are great passages for learning about theology proper.
From the Greek christos, christology is the study of the person and work of Jesus Christ. The study focuses on his roles as God and man, and as prophet, priest, and king, and introduces His work on the cross. Isaiah 53, and 61:1-2, Luke 4:18-19, John 1:1-18, Colossians 1:15-20, Philippians 2:1-11, the book of Hebrews and Revelation are a few definitive passages regarding christology.
From the Greek pneuma, meaning spirit, pneumatology is the study of the Holy Spirit. Pneumatology discusses the person and work of the Holy Spirit, especially in respect to His work in revealing Scripture (2 Peter 1:20-21), how He seals believers, guaranteeing their eternal life (Ephesians 1:13-14), how He brings people into the body of Christ (1 Corinthians 12:13), and how He helps believers to grow and bear fruit (Ephesians 5:17-18 and Galatians 5).
From the Greek angellos, we get our English word angel. Angelology is the study of angels, and includes demonology (study of demons) and satanology (study of Satan). Satan, for example, is discussed at length in passages like Genesis 3, Job 1, Ezekiel 28:11-19, Ephesians 6:13-17, 1 Peter 5:8, and Revelation 20.
Anthropos in the Greek is translated man. Anthropology is the study of humanity. This study considers humanity's creation and initial condition (Genesis 1-2), fall and condemnation (Genesis 3, Romans 5), and ultimate need for God’s grace (Romans 3, and Ephesians 2).
The Greek word for sin is hamartia. Hamartialogy is the study of sin. Of special emphasis in this study is how sin began (Ezekiel 28, Genesis 3), and its universal effects on humanity (Genesis 2:17, Romans 1:18-21, 3:23 and 6:23).
From the Greek word soteria, meaning deliverance or salvation, soteriology is the study of salvation. Thankfully, God provided a solution to the problems discussed in hamartialogy. Salvation is and always has been by grace through faith in Him (Genesis 15:6, Habakkuk 2:4, and Ephesians 2:8-9), and results in a new position for believers (2 Corinthians 5:17, and Ephesians 1), provides the opportunity for a new walk (Romans 12:1-2, Ephesians 4:1-3), and a new ultimate destiny (John 3:16, 17:3, 1 Peter 1:3-5).
This topic of theology is an important one, because God created and chose Israel for a special purpose (Genesis 18:19), made promises to the nation (Genesis 22:16-17, and Jeremiah 31:31-34), and has a future for Israel (Jeremiah 33:21-22, and Romans 9-11), and will be glorified through Israel (Jeremiah 14:21, and Romans 11:25-36).
This is the study of the ekklesia, or the assembly—the church. Ecclesiology considers the beginning of the church (Matthew 16:17-18, and Acts 2), its makeup (Ephesians 2:13-22), its relationship to Christ (Ephesians 5:21-33), its blessings (Ephesians 1:3), and its future (John 14:1-3, 1 Thessalonians 4:13-17, and Revelation 19:11-14).
From the Greek term eschatos, meaning last things, eschatology is the study of last things. Its focus is on still yet unfulfilled prophecy to Israel (Jeremiah 31, and Daniel 9), to the nations and to unbelievers (Revelation 4-19, 20:11-15), to the church (John 14:1-3, and 1 Thessalonians 4:13-17), regarding Christ and His kingdom (2 Samuel 7, and Revelation 20-22), Satan and judgment (Revelation 20:10), and the renewing of all things (Revelation 21-22).
When reading the Bible, it is helpful to think about which of these categories is being discussed. In doing so, the observant Bible student will begin to realize how interrelated are the books and teachings of the Bible—they are cohesive and connected. Consequently, what we understand in one area will necessarily influence (or even dictate) what we understand in another area. So it is vitally important that we be aware of the various issues discussed in the Bible, and to be aware of their relationships.