The Most Holy Trinity is the central and most profound mystery of the Christian faith and life. While we human beings can grasp certain aspects of this ultimate truth about God, precisely as a mystery, a full understanding is beyond our limited human comprehension. Yet, this deep mystery of God’s inner life and essence is also one of the most informative, in that, reflecting on the Trinity can shed invaluable light on what it means to be a human person.
Throughout history and in cultures throughout the world people have, by reason alone and after much consideration, concluded that God exists. Yet, we could devote ourselves to study over several lifetimes and never come to the conclusion that God is a Trinity of persons – one and yet three: Father, Son, and Holy Spirit. We know this truth and other divine mysteries in our human weakness only because the Lord has revealed them to us. And he has revealed this truth not as a matter of curious theological trivia disconnected from our everyday lives, but in order to share his divine life with us.
The mystery of the Blessed Trinity, as the mystery of God in himself, is “the source of all the other mysteries of faith, the light that enlightens them. It is the most fundamental and essential teaching in the ‘hierarchy of the truths of faith’” (CCC 234).
Since the earliest days – since before the Church was born at Pentecost – the Christian faith has been Trinitarian. When Jesus descended into the water at his baptism, for example, the bystanders hear the Father’s voice and see the Holy Spirit descend as a dove (Matthew 3:16-17). Later, Jesus will instruct his followers to “make disciples of all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Spirit” (Matthew 28:19). Likewise, Saint Paul offered blessings with a Trinitarian formula (2 Corinthians 13:13) and the blessings and prayers of the early Church reflect this faith in the Trinity.
The essential elements of this divine mystery are that we worship one God who is an eternal loving communion of three Persons – Father, Son and Holy Spirit – who are all equal in power, all co-eternal, and all divine. One divine nature, they differ only in that the Father is not the Son; the Son is not the Father; the Spirit is not the Son; the Spirit is not the Father. While this mystery of one and yet three might at first seem contradictory and irrational by human reckoning, if we delve deeper, we will find, like the other paradoxes of the faith, an amazing and profoundly life-changing truth.
The doctrine of the Trinity can perhaps best be understood by Scripture’s most compact definition of God: “God is love” (1 John 4:8, 16). Love is by its very nature relationship – it requires an “other.” The fullness of love is also by its very nature unitive. More than a mere association of individual persons, in the fullness of love there is a communion of persons – the multiplicity become one.
The Catholic author G.K. Chesterton observed that the Trinity is “simply the logical side of love.” Within God himself is Someone who loves and Someone who is loved, and there is the Love, who is a living reality as well. There is the Father and the Son, and the love which proceeds from them is not merely some warm sentiment, but a Person – the Holy Spirit.
Here too is revealed the essence of humanity. Made in the image and likeness of God – in the image and likeness of the Trinity – human beings, made male and female, are relational beings made to live in a loving fruitful communion of persons.
We see this in a particular way in the union of man and woman in marriage. As Pope Francis notes, “the couple’s fruitful relationship becomes an image for understanding and describing the mystery of God himself” as a communion of love (Amoris Laetitia, 11). That is, “the family is entrusted to a man, a woman and their children, so that they may become a communion of persons in the image of the union of the Father, the Son and the Holy Spirit” (Id., 71).
As a visible sign of the Trinity, marriage and family are in turn a sign of our heavenly Father’s greater plan for all humanity, that all of his creation be united as one in and through him – a communion of saints. That is what God wants for you and me – to love and be loved – and nothing could be more wonderful, more vibrant and alive, than to share in this way in the life of the Trinity.
This blog post draws from passages of my book “Faith that Transforms Us: Reflections on the Creed (2013).”