“Remember you’re speaking as a Catholic,” St. Augustine thundered once in a sermon.
But he wasn’t talking about the sacraments. He wasn’t talking about bishops or morality or vestments either, nothing like that. Remember you’re Catholics! What he was talking about was the Trinity, our “most orthodox faith, that the Father, Son, and Holy Spirit are one inseparable trinity; one God, not three gods.”
Without such belief there is no Catholic faith; that’s what St. Augustine was implying. “Our faith, after all, that is to say the true faith, the right faith, the Catholic faith,” he said, “is not a bundle of opinions and prejudices but a summary of biblical testimonies, not riddled with heretical rashness, but founded on apostolic truth.”
To be exact, he was preaching on one of the finer points of trinitarian theology, on the doctrine of inseparable operations, but I don’t want to talk about that. It’s complex; you can research that yourself. Rather, the simple point I want to make, borrowing St. Augustine’s homiletic zeal, is that the Trinity matters, that your belief in the Trinity matters — eternally, in fact.
The ‘central mystery of the Christian faith’
As the old Athanasian Creed begins, “Whosoever will be saved, before all things it is necessary that he hold the Catholic faith … And the Catholic faith is this, that we worship one God in Trinity and Trinity in Unity.”
The Catechism of the Catholic Church calls the Trinity the “central mystery of the Christian faith.” That is, it’s the divine mystery making all other sacred mysteries saving mysteries for us. No Trinity, no Baptism. No Trinity, no Eucharist. You get the point. That’s why it matters; it’s saving truth.
But how on earth do we get our heads around it? First, we should admit there are limits to our capacity for such knowledge. Theological vocabulary is helpful, analogies too. St. Augustine, for instance, employed analogies like lover, the beloved and love and, more famously, memory, understanding and will — those faculties found in a single soul — to try to explain it.
Exactly 1700 years ago, the fathers of Nicaea approved the word “homoousios” to try to articulate the relationship between the Son and the Father. “Consubstantial” is how that word is translated, and we recite it every Sunday, professing our faith that, yes, Jesus is of the same substance as God the Father, “true God from true God.”
Yet our knowledge of the Trinity comes first from our experience of the Trinity; or to be more precise, it comes first from our experience of Christ in Trinity. As St. Augustine said, our trinitarian faith is a “summary of biblical testimonies.” That is, the Nicene Creed is a concise and orthodox articulation of the whole of biblical teaching.
Seeking peace in the Trinity
But the creed also articulates our biblically authentic experience of Christ. That is, when we encounter the biblical Christ, we encounter him as one of the Trinity. As much as the Nicene Creed makes theological statements, more fundamentally it describes how we experience the biblical Christ. This, I take it, is what the theologian Khaled Anatolios, in his book “Retrieving Nicaea,” means when he says that our knowledge of the Trinity is first about being “incorporated into trinitarian life.” That is, the Trinity is what we come to know as we come to know Christ — the Son of the Father, who with the Father gives the Spirit to believers (Jn 14:26; 15:26).
Take this Sunday’s reading from Romans 5:1-5. It’s describing the Christian experience. Having faith in Christ, the Spirit is given (just as Jesus repeatedly promised in John’s Gospel) to the believer, which establishes for that believer peace with God.
| June 15, 2025 – Solemnity of the Most Holy Trinity |
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| Prv 8:22-31 Ps 8:4-5, 6-7, 8-9 Rom 5:1-5 Jn 16:12-15 |
Peace with God the Father through Jesus Christ in the gift of the Holy Spirit: That is the trinitarian experience Paul is describing. That’s what I mean by saying our knowledge of the Trinity comes first by way of our experience of the Trinity, of Christ in the Trinity. We first fall in love with Christ, we believe in him, and then the Trinity is revealed in the gift of the Holy Spirit as it’s poured into our hearts (Rom 5:5).
The mystery is mysterious, but the take-home point is simple. The Trinity matters, it really does. Don’t let anyone tell you otherwise. It names our deepest, most biblical, experience of Christ, a salvific experience. Which is why the Church calls us to celebrate this solemnity — to remember we are Catholics.
