The Church celebrates this Sunday the blessed, Holy Trinity. God is Three and One. In the calendar, Trinity Sunday follows Pentecost. Pentecost was the pouring of the Spirit (The Third Person of the Holy Trinity) upon an infant Church. Pentecost enabled the Bride of Christ to be the instrument of change in the world. She has become the fiery sword that conquers evil and puts foreign armies to flight. Pentecost was the undoing of Babel. The unclean lips of Babel have become–by the Spirit– the clean lips of the messengers of Yahweh going to all the ends of the earth.
The Trinity seals this mission with divine approval. The Father, the Son, and the Holy Spirit have covenanted together to see that the divine promises are fulfilled. Trinity Sunday is the renewed call to go into the world not in the name of some unknown God, but in the Name of the True God who reveals Himself in Three Persons.
Furthermore, Trinity Sunday is the Church’s Catholic response to disunity. To believe in an apostolic and catholic Church is to affirm the Trinity. There can be no true unity without this affirmation. The Trinity shapes our catholicity. We are bound by it, and anything else is a cosmic betrayal. But beyond that, it is also the Church’s response to cults who thrive on denying the sacred Trinity. The Trinity is the Church’s proclamation that the Christian faith is not just any other faith, but a unique faith centered on the divine covenant made from eternity. The Father sends the Son, the Father and the Son send the Spirit. The Father loves the Son, the Spirit loves the Son and the Father. There is love forever within the relationship of the Trinity. In fact, love is Trinitarian. There can be no love in a God who is only One. This God has no equal love to share. But in the Trinity, the Father loves the Son equally, and the Son and the Father love the Spirit equally. Therefore, a denial of the Trinity–as the cults do–is a denial of true love.
Trinity Sunday also exhorts us to trust in God alone. This God who is love loves us and incorporates us into this Trinitarian love. Because He is love, we too are called to model this divine love in our communities.
We celebrate the Trinity because we are shaped as a Trinitarian people: to love one another and to enter into this eternal feast with God as head, and we as body.