Let’s just acknowledge at the start that this day, the solemnity of the most Holy Trinity, can be vexing for anyone with a particular theological interest. As a theologian by training, I’m sympathetic: it is very difficult to listen to anyone else’s homily on Trinity Sunday, because it is literally the easiest day to fall into accidental heresy. Let’s pray that I avoid doing so!
Why do we have this day in the first place? Isn’t the Trinity central to our faith every day? Well, yes—which is why this particular day took a while to develop. There were liturgical forms related to the Trinity in the early Middle Ages, but Stephen of Liège, in the tenth century, was the best-known proponent of the liturgical devotion to the Trinity. It wasn’t until the fourteenth century, in 1334, that Pope John XXII mandated this day for the whole of the Latin Church. He did so only after John Peckham, archbishop of Canterbury, in the late thirteenth century, had composed a new office for the Trinity, and that following the even more famous St. Thomas Becket, who popularized the devotion by mandating it for the English Church in 1162, following his consecration as bishop on the first Sunday after Pentecost of that year.
So in the Ordinariates, we might point out that this day of devotion in the entire Latin Church has its foundation in the English tradition. Much like with Corpus Christi, next week, the English Church in the late Middle Ages very much led the way when it came to popular devotions—right up until the moment that Henry VIII cut it all off.
But what should we make of a day devoted to doctrine, apparently, which is so very different from the other feasts and commemorations that crowd the calendar, most of which are focused on particular events?
I do not know exactly what motivated John XXII, or Thomas Becket, or Stephen of Liège, or John Peckham. Devotion to the Trinity is not, in a certain sense, special; it is simply devotion to God, who is Trinity. This is why some of the earlier bishops and popes didn’t go for a special day on the calendar: isn’t every day devoted to the Trinity? In a way, it’s like having a special day for Jesus—which is weird, because nothing we do makes any sense without Jesus.
If we think through this, though, it becomes obvious that even though every day, every Mass, every Sunday, is because of and about Jesus, there are still certain days in which the mystery of his life, death, and resurrection become clearer. Even the greatest of all feast days, Easter Sunday, is, in a way, unnecessary, because Easter is the reason that we celebrate every other Sunday. Yet it is the source of those other Sundays. It is what gives them their meaning.
In a different but related way, the Church sees fit to mark this day as Trinity Sunday because, after Pentecost’s clear revelation of the Holy Spirit, the mystery of the three divine persons is now, in the order of revelation, fully established.
But it is more than simply a dogmatic affirmation. We could do that by other means, in the end. And we do—in confirmation, baptism, holy orders—the various places in which trinitarian faith has to be clearly expressed. We do it today, I think, following the reading from Deuteronomy, for a more specific reason: “Has any god ever attempted to go and take a nation for himself from the midst of another nation, by trials, by signs, by wonders, and by war, by a mighty hand and an outstretched arm, and by great terrors, according to all that the Lord your God did for you in Egypt before your eyes?”
As one theologian has said, “God is whoever raised Jesus from the dead, having first raised Israel out of Egypt.” We can talk all we want about the Trinity in philosophical terms, but we need to appreciate the fact that this doctrine, this dogma, comes to us not first through abstract metaphysical thinking, but through the concrete work of God in history. The Trinity is not some sort of escape from the historical experience of faith. Trinitarian doctrine comes directly from this encounter with the God who is Father and Son and Holy Spirit, in the raising of Israel out of Egypt, in the resurrection of Jesus from the dead, in the indwelling of the apostles at Pentecost.
There is no substitute for this historically grounded faith. We can offer speculative thinking—like St. Augustine, St. Anselm, or Richard of St. Victor, to name just a few writers on the subject—in which we try to explain the rationality of the Trinity. But in the end, these rational explanations fall short if they aren’t grounded in historical experience. And that is because human nature is historical, temporal. We cannot love what we cannot know, and we cannot know what we cannot experience.
This is why we can think of the solemnity of the Most Holy Trinity as the most Catholic of feast days: because the celebration of a doctrine is inseparable from the experience of the doctrine. How can we celebrate the Godhead without understanding that the Godhead has become flesh and has promised to be with us in certain definite signs: in baptism, in the Eucharist, in the forgiveness of sins?
I don’t want to be a disappointment, but this is not the day when the dogma of the Trinity can be fully explained. That is something we can know only in heaven, by seeing what is, for now, conveyed mostly by hearing and by faith. In this life, good trinitarian teaching primarily consists in stating negations. God is three, but he is not three gods. He is one substance, but the three persons are not confused with one another. Even that most important word in trinitarian theology, person, is an iffy translation of the Greek hypostasis, which, according to many of the fathers, is more of a placeholder term than anything else. We need, that is, a word to use in answer to the question “three what”? The fact that we use the word person, or hypostasis, does not mean that we know what the persons are in themselves. Those who have studied and meditated on the triune relations at some length, like Aquinas, find themselves increasingly aware of how little they know, even while their conceptual framework and vocabulary grow.
Now, don’t hear me saying that we should reject learning or understanding. But today’s feast is a celebration of God’s revelation of himself, and of man’s gratitude in receiving that revelation. The confession of faith in the Trinity is not one doctrine among others—and maybe this is why it has a privileged place in the Church calendar. It is the road we are walking on as well as the destination; it is the grammar and the content of our speech. The confession is a statement about what is true, to be sure, but even more it is an invitation: for in giving us a glimpse into his innermost being, God is saying to us, “Come follow me.” Following Jesus isn’t just a matter of imitating a rabbi from first-century Palestine; it is entering, through him, into the mysterious ground and end of our being, the source of all power, wisdom, and goodness.
And so if we want to more deeply apprehend the Trinity, if we want to see the inner workings of the Love that is the cause of all existence, we have to first seek Jesus. Sure, we can think deep thoughts, explore big concepts—yet personhood is a mystery. It is a mystery for human persons . . . how much more so for divine persons? We can know it only from the inside, so to speak. And the only way in is Christ: to love him, to know him, to find ourselves in him, and to make him known.
Blessed art thou, O Father, Son, and Holy Spirit: praised and exalted above all for ever.