On the first Trinity Sunday in my new call, I dutifully took a stab at preaching on the mystery of the Trinity, after which one of the dearest saints and most astute theologians in the congregation remarked to me, “I have worshiped here all my life, and this is the first sermon I have ever heard on the Trinity! I learned so much today, thank you!” I tried to hide my pride at following the lectionary in my preaching, no matter how difficult the texts – something my predecessors there had apparently avoided.

A year later, I preached again on the Trinity. After church, this same lovely saint told me, “I have worshiped here all my life, and this is the first sermon I have ever heard on the Trinity…” I learned something important that day about not taking myself too seriously as a preacher!

Christians have struggled with this doctrine for two thousand years. It defies understanding, and all metaphors for it fall short. The Trinitarian “formula” – Father, Son, and Holy Spirit – appears just once in the Bible, at Jesus’ Great Commission.

Yet the New Testament is replete with attributions of divinity to each of the three Triune Persons. For instance, Jesus’ resurrection is said to have been accomplished by the Father, by the Son himself, and by the Spirit. Each is distinct from the other – something evident in this year’s lectionary texts for the day – yet they are one. Each bears the full power and beauty of the Divine, and each is rightfully worshiped.

In the creation story, God says, “Let us make humankind in our image, according to our likeness.” One of the primary words for “God” in the Hebrew Scriptures, Elohim, is plural. One God. Yet plural. The mystery of the “Godhead” is not just a Christian innovation.

Theologians have wrestled with the metaphysics of this impossibility. John Calvin teaches that “God is One” is one of three cardinal Christian doctrines. (The others he cites are “Christ is God” and “God is merciful.” Institutes of the Christian Religion IV.1.12.) Yet he goes to great lengths to elucidate the doctrine of the Trinity.

Perhaps the best way to approach Trinity is not as an idea, but as a description of how God lives and moves. And as such, it offers a model for how we are created to live and move. Jesus prays that his followers would be one, just as he and the Father are one, echoing the Genesis story that God created us in the divine image.

This is the biggest human problem – living and moving in a way that rightly reflects the divine image we bear. The essence of our sin is our failure to live with each other in the way the three Persons of the Godhead live together. With mutual respect and deference. In the Bible, the three Persons of the Trinity seek to glorify each other rather than themselves, something we do with each other by considering each other better than ourselves. (Philippians 2:3)

We may never grasp how the Persons of the Trinity are one yet three, three yet one. But this we can grasp – our calling is to live with each other in the way the Persons of the Trinity do.

Not only is this our calling. It is our destiny. It’s what Jesus prays for, and it’s safe to say that Jesus gets what he prays for. He doesn’t force it on us, but he is willing to wait until we come to repent from our “warring madness” – no matter how long it takes. (2 Peter 3:8-9)

How long will we push against the current of our destiny? Beloved, living in enmity with each other is exhausting. It drains from us all the joy and energy that is rightfully ours. It’s for our own good to live at peace with each other. We are destined to sit at table together in the Kingdom; how much better if we learned now to live that way, rather than fighting it all the way to heaven’s gates!

Living in unity benefits us greatly, but the benefit is not only – or even primarily – our own. In his prayer that we be one, as he is one with the Father, Jesus elaborates that this unity is “so that the world may believe.” When we ignore or demean or demonize each other, the opposite happens. Our disunity destroys the public credibility of our Gospel proclamation.

Let me be plain: Disunity in the church is one of the greatest obstacles to effectual evangelism.

Trinity is a practical, not just a theoretical doctrine. We show that we “get” it by how we live together. We rightly require a faithful, orthodox articulation of the doctrine from all whom we approve for ordination to ministry of Word and Sacrament. But the doctrinal articulation matters little if it does not shape how we live.

Are we truly a Trinitarian church? The answer lies not only in our creeds, but in our practices.

Yours in divine communion,