Sermon For Trinity Sunday

One Name, Three Persons, One Life Given To Us

The Gospel of Matthew ends not with a farewell but with a commission, and the commission begins with a name. Not names, plural, as though the Father and the Son and the Holy Spirit were three separate powers to be invoked in sequence. One name, singular, into which every baptized person is drawn. "Go, therefore, and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit." That single name, shared across three persons, is where Matthew leaves us. It is also, on this Trinity Sunday, exactly where we begin.

Now I want to be honest with you from the start. The doctrine of the Trinity is not easy. It has never been easy. The church spent centuries working out its language, and even after the great councils, the mystery did not dissolve. It deepened. But here is what I want you to hold onto this morning: the Trinity is not primarily a puzzle to be solved. It is a reality to be inhabited. The triune God is not a theological examination question. The triune God is the one in whom we live and move and have our being. And if that is true, then understanding something of who this God is matters enormously for how we worship, how we love, how we go out into the world, and how we endure when the world is hard.

So let us think carefully together, because the doctrine of the Trinity, properly understood, is not abstract information. It is the very shape of the Christian life.

The Doctrine Defined

Let me offer you one sentence as a foundation. The doctrine of the Trinity teaches that the one God exists eternally as three distinct persons, Father, Son, and Holy Spirit, equal in nature, undivided in essence, and distinguished by their relations to one another.

That sentence is dense, and we will unpack it. But notice what it does not say. It does not say there are three gods. It does not say there is one God who wears three different masks at different times, sometimes appearing as Father, sometimes as Son, sometimes as Spirit. Both of those ideas have been taught, and both of them are wrong. The first is called tritheism. The second is called modalism. The church has rejected both, not out of stubbornness, but because neither of them fits what the Scriptures actually show us.

What the Scriptures show us is something far more wonderful and far more strange. They show us a God who is, within himself, a communion of persons. A God who, before any creation existed, before any human being drew breath, was already in relationship. The Father loving the Son. The Son glorifying the Father. The Spirit proceeding from and bearing witness to both. This is not a God who needed to create us in order to have someone to love. This is a God who is love in his very being.

The Biblical Foundation

Turn with me to two passages that anchor this homily.

The first is Matthew 28, verses 16 through 20. The eleven disciples have gathered on a mountain in Galilee. The risen Christ stands before them. Some worship. Some doubt. Both responses are honest, and Matthew does not hide the doubt. Then Jesus speaks, and what he says reshapes everything. "All authority in heaven and on earth has been given to me. Go, therefore, and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe everything I have commanded you. And remember, I am with you always, to the end of the age."

Notice the structure of that commission. It is grounded in the authority of the Son. It is carried out in the one name of the triune God. And it is sustained by the ongoing presence of Christ through his Spirit. The Trinity is not a footnote here. The Trinity is the engine of the mission.

The second passage is 2 Corinthians 13, verse 13, which many of us know as the apostolic blessing spoken at the close of worship. "The grace of the Lord Jesus Christ, and the love of God, and the fellowship of the Holy Spirit be with you all." Three persons. Three gifts. One blessing. Paul does not explain the Trinity in this verse. He simply speaks from within it, as a man who has come to know that the grace he received on the road to Damascus, the love that held him through shipwreck and imprisonment, and the fellowship that sustained him in his ministry, all of it flows from one God who is Father, Son, and Spirit.

These two passages together give us the shape of what we need to understand. The Trinity is the foundation of Christian mission, and the Trinity is the source of Christian life.

Clarifying The Paradox

Now let me address the question that is almost certainly forming in some of your minds. How can one God be three persons? Is this not a contradiction?

It would be a contradiction if we were saying that God is one person and three persons at the same time and in the same sense. But we are not saying that. We are saying God is one in essence and three in person. Those are different categories. The oneness refers to what God is. The threeness refers to who God is, or rather, who the three are within that one divine being.

An analogy can only take us so far here, and I want to be careful not to push any analogy past its limits. But consider this. A single piece of music can be simultaneously melody, harmony, and rhythm. Remove any one of those and you no longer have the same music. They are distinct, yet inseparable, and together they constitute the one thing. The analogy breaks down, as all analogies do, because the Father, Son, and Spirit are persons, not components. But it gestures toward the truth that unity and distinction are not always enemies.

What the church has always insisted is this: the three persons are not parts of God, as though God were divided into thirds. Each person is fully God. The Father is not one-third divine. The Son is not a lesser deity. The Spirit is not a divine afterthought. Each is fully and wholly the one God, distinguished not by degree but by relation. The Father begets the Son. The Son is begotten. The Spirit proceeds. These relations are eternal, not sequential. There was never a time when the Son did not exist, or when the Spirit was absent.

This matters because if the Son is less than fully God, then what was accomplished on the cross is less than fully sufficient. If the Spirit is less than fully God, then the life given to us in baptism and sustained in us through prayer is less than fully divine. The full weight of our salvation depends on the full deity of all three persons.

The Implications For Worship, Love, And Mission

Now let us move from truth about God to what that truth means for us.

First, the Trinity tells us that love is not something God decided to do. Love is something God is. Before the creation of the world, the Father loved the Son, and the Son loved the Father, and the Spirit was the bond and expression of that love. When the First Letter of John says "God is love," it is not offering a sentiment. It is making a claim about the inner life of the Trinity. And this means that when you are loved by God, you are being drawn into something that was already happening before you arrived. You are not creating love in God by being lovable. You are being welcomed into a love that is eternal.

Second, the Trinity tells us that the church is not an organization that worships a God who stands outside it. The church is a community drawn into the life of the Trinity. When we gather at this Table, we do not merely remember a historical event. We participate in the ongoing self-giving of the Son to the Father, in the Spirit. The Eucharist is Trinitarian from beginning to end. We come to the Father, through the Son, in the Spirit. The liturgy we share in this place is not our invention. It is our participation in something that was already in motion before the world began.

Third, the Trinity tells us something essential about Christian mission. Go back to Matthew 28. The command to make disciples is not a program the church invented. It flows from the nature of God himself. A God who is, within himself, a communion of persons, is a God whose very being moves outward in love. Creation is an act of that outward movement. Redemption is an act of that outward movement. The mission of the church is an act of that outward movement. We go because God goes. We love because God loves. We welcome the stranger and the seeker because the triune God is, by nature, a God who draws others in.

And fourth, the Trinity is the ground of Christian endurance. Paul's blessing in 2 Corinthians 13 was written to a congregation that was struggling, divided, and worn. He does not offer them a strategy. He offers them the grace of the Lord Jesus Christ, the love of God the Father, and the fellowship of the Holy Spirit. Grace for the failures they cannot undo. Love that does not depend on their performance. Fellowship that holds them together when everything else is pulling them apart. That blessing is not a formality. It is a lifeline. And it is ours as well.

A Call To Trust, Adore, And Live Differently

So here is where I want to leave you this Trinity Sunday.

You are not being asked merely to understand the Trinity as a doctrinal formula. You are being invited to live inside it. To receive the grace that flows from the Son's self-giving. To rest in the love that the Father has poured out on you. To walk in the fellowship that the Spirit makes possible between you and God, and between you and one another.

The disciples on that Galilean hillside heard the risen Christ speak a name over them. One name. The name of the Father and of the Son and of the Holy Spirit. That name was spoken over you in your baptism. You were not simply enrolled in a religion. You were named into a relationship, a relationship that is eternal, that is unbreakable, and that is the deepest truth about who you are.

Go, then. Make disciples. Baptize. Teach. And remember: the one who sends you is the same one who promises to remain with you, always, to the end of the age.

That is not a doctrine to be filed away. That is a life to be lived.

Sources Consulted

Holy Bible, Christian Standard Bible. Holman Bible Publishers, 2017. Matthew 28:16-20; 2 Corinthians 13:13.

The Book of Common Prayer. Church Publishing, 1979. Eucharistic Prayer A; the Baptismal Covenant.

Athanasius of Alexandria. On the Incarnation. Translated by John Behr. St. Vladimir's Seminary Press, 2011.

Augustine of Hippo. The Trinity. Translated by Edmund Hill, O.P. New City Press, 1991.

Alister E. McGrath. Christian Theology: An Introduction. 5th ed. Wiley-Blackwell, 2011.

N. T. Wright. Matthew for Everyone, Part 2. Westminster John Knox Press, 2004.