D. A. Carson Quotes
Systematic theology will ask questions like "What are the attributes of God? What is sin? What does the cross achieve?" Biblical theology tends to ask questions such as "What is the theology of the prophecy of Isaiah? What do we learn from John's Gospel? How does the theme of the temple work itself out across the entire Bible?" Both approaches are legitimate; both are important. They are mutually complementary.
Carson, D. A. "Introduction to Biblical Theology." NIV Zondervan Study Bible, edited by D. A. Carson, Zondervan, 2015.
Early Christianity had a wide diversity of sect and opinion.
Donald Arthur Carson is Emeritus Professor of New Testament at Trinity Evangelical Divinity School and co-founder of The Gospel Coalition. He is a prominent evangelical scholar and author.