Below is a post from Crossway Called The History of Christian Theology in 1,000 Words written by Gerald Bray, author of God Has Spoken: A History of Christian Theology (October 2014).
Theology is essentially the way in which the Christian church has received the Word of God revealed to us in the Bible and in Jesus Christ. The early church inherited the Hebrew Scriptures (our Old Testament) and accepted them as a true picture of who God is and what he is like. He is absolutely unique and sovereign over everything that exists, which he created out of nothing and for a purpose.
Furthermore, he gave human beings the right to rule in his name and established them in fellowship with himself. Nonetheless, our first parents were tempted away by Satan and sinned against God. The rest of the biblical story recounts how God’s plan to deal with this rebellion, first by choosing a special people for himself (Israel) and then by giving them prophets to teach them how to respond to him.
The first Christians inherited all of this from their Israelite forbears. However, in the person and work of Jesus Christ they came to a new and deeper experience of God. In the Old Testament, God appeared as One, dwelling among his people yet remaining largely unapproachable. He was the fire in the burning bush that could not be touched. He was present in the Holy of Holies, which was off limits to all but the high priest, who himself could only enter the inner sanctuary but once a year.
In Christ, all this changed.
Jesus broke down the barriers separating God from his people, revealing more about who he is and how he works. Believers are now seated in the heavenly places, with access to God’s presence through the indwelling Spirit of the Son, who comes from the Father. The Christian experience of God is therefore Trinitarian.
The person of the Father was the focus of Jesus’s ministry. He taught his disciples to think of God as Father, because otherwise they could not have understood Jesus as the Son. The Aramaic word ‘Abba’ (Father) was so characteristic of Jesus that it is preserved in the Gospels as a reminder of him.
Next came the work of the Father, who was understood as both the Creator and the Redeemer. There were people who thought that this was impossible, because, if a perfect God had created the world, the world would also be perfect and would not need redemption. They therefore concluded that the Creator was an inferior deity, whose work was perfected by the Father of Jesus Christ. If that idea had been accepted, the Old Testament would have been rejected as the revelation of a lesser being. Jesus would not have fulfilled its promises, but overturned its false teaching. This idea was contrary to his purposes, and so the early church had to reject it by insisting that evil is not intrinsic to creation, and that the God who made us is the same God who saves us.


