The Feast of the Holy Trinity can sometimes make people nervous. Priests often joke that Trinity Sunday is one of the hardest Sundays of the year to preach. We hear words like “three persons in one God” and “one substance”, and we can quickly begin to feel that the whole thing is impossibly complicated. But perhaps we begin in the wrong place. The Trinity is not a puzzle for clever people to solve. It is the revelation of who God truly is. And what God reveals is not confusion, but love. We call the Trinity a mystery not because it is nonsense, but because it is wonderful beyond our full understanding. There are many things in life which are like that. Love itself is mysterious. Human relationships are mysterious. Beauty, music, sacrifice, forgiveness – these things cannot simply be reduced to formulas. We experience them, we live them, and they shape us deeply.

So too with God. Again and again in the Scriptures, we see Father, Son and Holy Spirit acting together. At creation, the Father speaks his eternal Word and creates through the breath of the Spirit. In the Old Testament, the Spirit speaks through the prophets preparing the way for Christ. At the Annunciation, the angel brings the message of the Father and Mary conceives the Son through the power of the Holy Spirit. At the baptism of Jesus, the heavens open, the Spirit descends like a dove, and the Father declares: “This is my beloved Son.” (Matthew 3:17, ESV) At the cross, the Son offers himself to the Father in love for the salvation of the world. After the resurrection and ascension, Christ sends the Holy Spirit upon the Church at Pentecost. Again and again, Father, Son and Spirit move together in one divine action of love.

This is important because sometimes people imagine the Trinity as though God were divided into parts. But God is one. The Father never acts without the Son and Spirit. The Son never acts apart from the Father and Spirit. The Holy Spirit never acts independently from the Father and the Son. The Holy Trinity is eternal communion, eternal love, eternal unity. And this is not merely abstract theology. It matters profoundly for our lives. Every time we make the Sign of the Cross, we place ourselves within the life of the Trinity. Every prayer we offer is directed to the Father, through the Son, in the Holy Spirit. Every Mass is an encounter with the life of the Trinity. We ask the Father to send the Holy Spirit upon the gifts of bread and wine so that they become the Body and Blood of his Son. The Trinity is not distant from us. The Trinity surrounds us, sustains us, and draws us constantly into divine life. St Augustine once said that if we could fully understand God, then what we understood would not be God at all. Yet Augustine also insisted that the closer we grow to God, the more we discover that God is love. That is the key to today’s Gospel. “God sent his Son into the world, not to condemn the world, but in order that the world might be saved through him.” (John 3:17, ESV)

God does not withdraw from humanity. God reaches towards humanity. The Father sends the Son. The Son gives his life for us. The Holy Spirit dwells within us. The whole movement of salvation is the movement of divine love. Pope Benedict XVI wrote that Christianity is not first about an idea, but about an encounter with a person, Jesus Christ. And through Christ we are drawn into the life of the Trinity itself. That means that our Christian life is not simply about following rules or preserving traditions. It is about allowing ourselves to be caught up into the life and love of God. And this changes the way we live. If God is eternal communion, then isolation, hatred and selfishness can never satisfy the human heart.

We are made for relationship. We are made for forgiveness. We are made for love. The Trinity reveals not only who God is, but also who we are called to become. In a fragmented world, where people are often lonely, suspicious and divided, the Trinity reminds us that love is stronger than fear. Communion is greater than isolation. Mercy is greater than condemnation. And so today we do not merely admire the mystery of the Trinity from a distance. We are invited into it.