Divergent philosophies of Protestant worship
Historians observe that by Bach’s 18th century, the stream of Lutheranism was dividing into contentious currents. The Pietists stressed the need for “a living theology of the heart.” As part of their critique of dead orthodoxy, they called for simpler church services and simpler church music. Bach vehemently rejected these proposals, but he did embrace the Pietists’ emphasis on a Christ-centered religion in which the human heart was drawn by the affections to God’s love manifest in Jesus.
Before and during this time saw the evolution of the regulative principle of worship within Protestant practice. The regulative principle, in short, puts forth that “only those elements that are instituted or appointed by command or example or which can be deduced by good and necessary consequence from Scripture are permissible in worship, and that whatever is not commanded or cannot be deduced by good and necessary consequence from Scripture is prohibited.” In contrast, the normative principle holds that “whatever is not prohibited in Scripture is permitted in worship, as long as it is agreeable to the peace and unity of the Church.”
Conservative proponents of the regulative principle may hold to very specific interpretations of it, such as Psalms should be sung in corporate worship to the exclusion of all else; only the whole congregation should sing at once as opposed to special singers; instruments should be kept to a minimum or excluded completely, etc. However, even though the regulative principle itself sounds straightforward enough, there is a spectrum of interpretation and even within conservative Reformed circles, the understanding of the regulative principle is hardly monolithic enough that this take on it should be considered prescriptive for all congregations.
On the other side of the theological continuum from the Pietists, Bach knew Lutheran theologians who were moving in the direction of rationalism. As heirs of the Enlightment, they tended toward believing in the ability of the human mind to discover the secrets of the universe. Bach shared with these theologians a commitment to regularity and order, as the stunning precision of his compositions testified so masterfully. But he also recoiled from any rationalistic tendencies that detracted from the Bible’s depiction of human sinfulness and divine redemption in Christ.
Bach was his era’s most powerful exponent of Martin Luther’s theology and practice. Indeed, the great modern musicologist Jaroslav Pelikan has asserted that Bach might be considered among the premier expositors of Luther’s theology for any age. For Bach, the lodestar — musically, ecclesiastically, theologically, temperamentally, professionally — was Luther’s understanding of Christ and his work. As summarized in Martin Geck’s biography, “That [God] can be found only … through the suffering and cross of Jesus Christ and his followers, is an insight coming from Luther and one that Bach passed down in a great many different ways in the texts of his cantatas and passions but most of all in his music itself.”