Calvin Stapert explains why his  introductory volume on the theology and music of J.S. Bach follows the structure of the Heidelberg Catechism

I wanted to write a small book that would serve as an introductory guide to Bach’s text-related works, especially for listeners who would like use them devotionally.

I wanted to discuss specific works rather than make generalizations about the works as a whole, and I wanted to select and organize those works according to some theological basis.

The Heidelberg Catechism is the theological compendium I know best. It was the basis for my theological instruction as a boy, and I have heard it preached all my life.

But over the years I have also spent a good amount of time listening to Bach’s musical “sermons.” And, far from experiencing dissonance between Calvinist preaching based on the Heidelberg Catechism and the Lutheran preaching of Bach, I found them very much in accord. The preaching I heard in the Calvinist churches I attended and the music of Bach I listened to at home still seem to be very much in harmony. . . .

I hope that by providing key doctrinal statements from the Catechism, relevant Scripture passages, literal translations, and commentary on the texts and music, this book will make Bach’s theologically astute, artistically masterful, and religiously devout works more understandable for many listeners and hence make them more available as means for instruction, edification, and devotion.

—Calvin R. Stapert, My Only Comfort: Death, Deliverance, and Discipleship in the Music of Bach (Grand Rapids: Eerdmans, 2000), pp. xiii-xiv, xvii.