In a course on theology and beauty, I ask my students why music has been such a persistent feature of Christian worship across history and cultures. In essay after essay, they tell me that this is because music moves us emotionally. Of course this is true. Music engages our emotions and in this way enriches our worship.

Early Christian writers also recognized music's affective power. Just as often, however, they commended music for its powers of harmony—in both the musical and extramusical sense of that word. Music seemed to them a sounding image of rightly ordered relationships. Ignatius of Antioch writes: "In your concord and harmonious love, Jesus Christ is sung. . . . [So] become a choir, that being harmonious in love, and taking up the song of God in unison, ye may with one voice sing to the Father through Jesus Christ." For Ignatius, the harmony of believers is not simply a good organizational principle, or even a right behavior to be encouraged. Rather, the harmony of the church is a theological statement. When the church is "in concord," then "Jesus Christ is sung"—the person and character of Jesus are declared. For Ignatius, the church's unity has both a doxological function—it manifests God's glory—and a pedagogical function—it teaches.

This same conviction stands behind Paul's exhortation to the Ephesians: