You may have heard in the news how Pope Francis and Orthodox Patriarch Bartholomew have recently proposed some sort of meeting at Nicaea in 2025 to commemorate the 700th anniversary of the 1st Ecumenical council of Nicaea at which the famous “318 Holy Fathers” among other things drafted what we now call the Nicene Creed. (Actually, the Creed we recite at Mass is the product of the first two ecumenical councils – Nicaea in 325 and Constantinople in 381 – and is officially called the “Niceno-Constantinopolitan Creed” or “Nicene Creed,” for short).
The issue at Nicaea in 325 was the Arian heresy which denied the divinity of Christ, in response to which the Creed was composed, formally articulating the Church’s ancient faith in the Holy Trinity. The Preface of the Holy Trinity, which will be prayed at Mass today was composed sometime after that. Today’s feast of the Holy Trinity was first celebrated for certain in Belgium early in the 10th century and was finally included in the calendar for the whole Church in 1334.
According to a famous legend, Saint Patrick is said to have used a shamrock to teach the doctrine of the Trinity when evangelizing Ireland in the 5th century. The fact that he resorted to using a shamrock illustrates the difficulty we have when talking about the Trinity. But I think the principal problem perhaps is not so much that the Trinity is a supernatural mystery, which we can never completely understand, but rather that it seems such an abstraction, more like a philosophical idea than an expression of religious experience.
And yet, as Christians, our religious lives are thoroughly permeated by our faith in the Trinity. We begin Mass and most of our prayers with the Sign of the Cross – In the name of the Father and of the Son and of the Holy Spirit. The Collect at Mass is addressed to the Father through the Son in the unity of the Holy Spirit. When we recite the psalms in the Divine Office, we conclude each psalm with the Doxology – Glory to the Father and to the Son and to the Holy Spirit – and we do the same in our private prayers with each decade of the rosary. That doxology is amplified at Mass in the great hymn of praise to the Trinity that we sing on Sundays and feast just before the Collect – the Gloria.
If we seem sometimes to take the idea of the Trinity for granted, it may be because it seems to surround us all the time.
On the one hand, the doctrine of the Trinity expresses our uniquely Christian insight into the inner life of God – where the Son is the image of the Father, the Father’s likeness and outward expression, who perfectly reflects his Father, while the Holy Spirit in turn expresses and reveals the mutual love of Father and Son. At the same time, the Trinity also expresses something fundamental about how God acts outside himself. Who God is in himself is how God acts toward us. In terms of our religious experience, it is how God acts that reveals who God is.
Already in the Old Testament, God was revealing himself – as he did to Moses in today’s 1st reading, as one whose nature is revealed in how he acts toward us: a merciful and gracious God, slow to anger and rich in kindness and fidelity. It was to such a God that Moses prayed – as we all pray – do come along in our company … and receive us as your own.
It is, of course, the Son, consubstantial with the Father, who, as the visible image of the invisible God, came down from heaven, so that the world might be saved through him. Risen from the dead and seated at the right hand of the Father, the Son has sent the Holy Spirit upon his Church, which is the Body of Christ and the Temple of the Holy Spirit. The Holy Spirit is inseparable from the Father and the Son, in both the inner life of the Trinity and his gift of love for the world. The Holy Spirit unites us with the Father in the Body of Christ, the Church. Through the sacraments, Christ continues to communicate the Holy Spirit to the members of his Church.
So it is no merely theoretical abstraction that God's grace is given to us from the Father, through the Son, in the unity of the Holy Spirit. As the famous 4th-century Bishop and Doctor of the Church, St. Athanasius, wrote in one of his letters: When we share in the Spirit, we possess the love of the Father, the grace of the Son, and the fellowship of the Holy Spirit himself.
Hence, the Church faithfully follows St. Paul in praying: The grace of our Lord Jesus Christ, and the love of God, and the communion of the Holy Spirit be with you all!
Homily for Trinity Sunday, Immaculate Conception Church, Knoxville, TN, June 15, 2014.