This study of Mercersburg theology is neither Fundamentalist, Modern, nor Liberal. It is classically Reformed. The foundational insights of Mercersburg are the reality of Jesus Christ as the second Person of the Holy Trinity, and the developmental nature of the Christian church as the body of Christ. Philip Schaff demonstrated that there is a theme of faithfulness that runs throughout Christian history which is in the process of ongoing maturity. I have called this the progressive revelation of Jesus Christ in history, which means that more people are becoming increasingly aware of the reality of Jesus Christ, and that the clarity and veracity of Jesus Christ continues to increase. This study takes various observations and insights made in 1866 about Mercersburg theology and sets them into a contemporary context, but rather than discuss the theological issues it endeavors to express, clarify, and adjust some of the various elements as being faithful to Scripture and understandable to ordinary church people in the hope of continued renewal, revival, and reformation of Christ's churches.