Karl Barth (1886-1968) described theology as best done in the second person, that is, as response to God. When we gather for Mass, we offer our prayer to God the Father, through the Son, in the Holy Spirit—and the elements of the liturgy are some of the richest works of theology we will encounter. In the Gloria, we respond to the One who has called us, and who, by the Holy Spirit, gathers us for worship. We exalt God together, as a people acclaiming their king. But this is an extraordinary king, whose glory is eternally shared by the Son and the Holy Spirit. Not only that: the Son, whom we praise as ‘the Most High’ we also call by name—Jesus. And Jesus not simply ‘Only Begotten Son’ but also, simultaneously, ‘Lord God’ and ‘Lamb of God.’ He is the One who takes away the sins of the world, who takes away our sins and restores us to friendship with our heavenly King and Father.
The Gloria ought to draw our attention to the Trinitarian character of our worship. It might have been a popular hymn in the third century, but its theology is not in any way impoverished. As we sing the Gloria, we address the Father and the Son and (indirectly) the Holy Spirit. For all its apparent simplicity and repetition of phrases, the Gloria expresses, obliquely, the deepest mysteries of the faith: the Trinity and the Incarnation. We are invited to ponder the great glory of God and God’s boundless love for us as we join together in prayer. Let us do so joyfully.