When discussing theology, we must be aware that there are different ways within Christianity of approaching and organizing theology. My approach tends to stick to systematic theology though the other styles are useful and do I do find myself using them from time to time.
In Natural theology knowledge about God is derived primarily from nature and it usually places a heavy emphasis on reason and philosophy. A basic understanding of God can be gained from the natural world. It is difficult to see the complexity of a cell, the beauty of a forest, and the glory of a star filled night and not acknowledge that there is a God.
The heavens proclaim the glory of God. The skies display his craftsmanship. - Psalm 19:1 NLT
While all theology should be Biblical, Biblical theology places an emphasis on the unfolding of God’s revelation as it progressed through history. It is knowledge about God which is derived primarily from the study of the doctrines of the Bible arranged according to their chronology and historical background, such as a study of God in the Pentateuch or a study of the concept of a remnant in Israel, or like the verse below, the revealing of the mystery of the church age.
Now all glory to God, who is able to make you strong, just as my Good News says. This message about Jesus Christ has revealed his plan for you Gentiles, a plan kept secret from the beginning of time. But now as the prophets foretold and as the eternal God has commanded, this message is made known to all Gentiles everywhere, so that they too might believe and obey him. - Romans 16:25-26 NLT
Historical theology involves knowledge about God which is derived from studying the development of ideas over time. It is arranged around the major periods of history which brought changes to theology (e.g., Theology of the Early Church, Theology of Reformation, etc.). It is the study of the development and history of Christian doctrine. It covers the development of creeds, church councils, and heresies that have arisen and been dealt with throughout church history. It studies the development of the essential doctrines that separate Christianity from other beliefs.
God did not reveal it to previous generations, but now by his Spirit he has revealed it to his holy apostles and prophets. - Ephesians 3:5 NLT
Systematic theology is the division of theology into systems that explain its various areas. For example, many books of the Bible give information about the angels, but no one book gives all the information about the angels. Systematic theology takes all the information about angels from all the books of the Bible and organizes it into a system called angelology.
Systematic theology is about organizing the teachings of the Bible into categorical systems of ideas which theologians have agreed upon over the centuries (e.g., Bibliology, Christology, Pneumatology, Ecclesiology, Soteriology, etc.). Doing so encourages a more complete and consistent view of each topic.
For I have not hesitated to proclaim to you the whole will of God. - Acts 20:27 NIV
Dogmatic theology involves knowledge about God with an emphasis on those teachings and ideas which have the authoritative stamp of approval from the church. Dogma is a set of principles laid down by an authority as incontrovertibly true. A good example of dogmatic theology is a church’s statement of faith.
Then fourteen years later I went back to Jerusalem again, this time with Barnabas; and Titus came along, too. I went there because God revealed to me that I should go. While I was there I met privately with those considered to be leaders of the church and shared with them the message I had been preaching to the Gentiles. I wanted to make sure that we were in agreement, for fear that all my efforts had been wasted and I was running the race for nothing. - Galatians 2:1-2 NLT
Theology which is built upon any of the previous types of theology, but which emphasizes the practical ways of living out these ideas in our own lives today. It is the study of theology so that it can be used and is relevant to everyday concerns.
But don't just listen to God's word. You must do what it says. Otherwise, you are only fooling yourselves. - James 1:22 NLT