Here is a bold statement by Timothy George, church historian, and dean of Beeson Divinity School:
Church history is much more than the history of the church. Anyone well trained in the study of the human past can become an expert in the history of Christianity, the history of Christian thought, or the development of institutional and denominational church life. But church history is a theological discipline rooted in the self-revelation of the biblical God, the God who makes and keeps covenant with his people. As such, it is enormously relevant to the task of proclamation, the primary job of every God-called minister of the gospel. I dare to say that, apart from the direct study of the Holy Scriptures themselves, no discipline in the theological curriculum is more important for the sermon preparation of the preacher.
Timothy George, “SBJT Forum: Profiles on Expository Preaching,“ Southern Baptist Journal of Theology 3.2 (Summer 1999), 89.