This theological commentary is the first full-length work in English to consider Johanna Sebastian Bach's St John Passion in its entirety both the words and the music. Bach's oratorio is a globally popular musical work, and a significant expression of Lutheran theology. The commentary explaining the Biblical and poetic text, and its musical setting, line by line. Bach's Passion is shown to be the work of a master craftsman and trained theologian, in the collaborating and cultural milieu of eighteenth-century, Lutheran Leipzig. For the first time, this work makes much German scholarship available in English, including archival sources, and includes a scholarly translation of the libretto. The musical and theological terms are explained, to enable an interdisciplinary understanding of the Passion's meaning and continued significance.