Concerning his use of musical instruments, David is not the example given for us to imitate according to Calvin. Rather, in the Reformer’s interpretation, David uses the harp in bringing praise to theLord as an additional typological aspect to worship in the Old Testament. He explains that instruments in the worship service belong to the puerile phase of the church as part of the “pedagogy” of the law. They were aids employed by God before the coming of Christ to move the faithful of the Old Testament to even greater zeal as they praise him. Like other elements of worship during the old dispensation, instruments should be counted among the “shadows” which God used during the times before Christ. However useful they may have been as a help for “the old people” of Israel, Calvin asserts that musical instruments as such were not essential to true worship then and he implies that this is even truer for the Christian church today.
—Herman Selderhuis, Calvin’s Theology of the Psalms