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5 Ways the Doctrine of the Trinity Is Surprisingly Practical

Even the best metaphors fail to capture the complexities of God’s being. In fact, when Christians attempt to explain the Trinity, they often stumble into metaphors that sound suspiciously like the very heresies Trinitarian theology was developed to counteract!

But even if you conquer the intimidating task of explaining the meaning of the Trinity, you may face an even more momentous challenge: demonstrating why it matters.


Pastor and theologian Peter Leithart says that, far from being an abstract theological concept only for the most pedigreed theologians, the doctrine of the Trinity has profound, practical implications. And not just for the way we think about God; the Trinity should affect the way we live the Christian life.

The doctrine of the Trinity . . . is a practical doctrine. It tells us what God is like, it tells us what to be like, it says something about the kind of God we worship and the way God interacts with us and with the world. As we understand more and more what the Bible reveals to us about the Father, Son, and the Holy Spirit, the more practical this doctrine becomes.

Here are five ways the doctrine of the Trinity is surprisingly practical, all drawn from Peter Leithart’s Mobile Ed course on Trinitarian theology and his book Traces of the Trinity.

1. The Trinity distinguishes Christianity from other religions

Why does it make any difference if we say God is Father, Son, and Spirit, instead of just one person—like Allah? In this clip from his Mobile Ed course on Trinitarian theology, Leithart argues that the doctrine of the Trinity underscores the differences between Christianity and other religions.

If we jettison the doctrine of the Trinity, we forfeit one of the key doctrines that distinguishes Christianity from other monotheistic religions. What’s more, we’re left with a conception of divinity that fails to account for one of the most fundamental aspects of God’s being: love.

2. The Trinity enriches our understanding of righteousness

As demonstrated in the clip above, Leithart—like St. Augustine before him—roots the divine attribute of love in the very nature of the Trinity. But he goes on to argue that our understanding of every single attribute of God should be informed by the Trinity:

All the . . . attributes the Bible talks about are attributes of the triune God, and we can reason about all of these attributes in the context of Trinitarian theology. And unless we do, we are missing a large part of what these attributes mean.

For instance, Christians everywhere describe God as eternally righteous. But let’s imagine for a moment that God does not exist as a Trinity. If righteousness is meeting one’s obligations, and If God is only one person—what’s known as a unitarian view of God’s being—how could God be truly righteous? How could God be “righteous” before any other person existed?

Leithart says that no matter how you define it, the very concept of “righteousness” implies the existence of more than one person. A unitary being can’t have obligations. The most you could say is that such a one is “potentially righteous.”

Define righteousness however you like. Define righteousness as faithfulness in relationship. Define righteousness as justice. How can a righteous God be truly righteous, actively righteous, if he is only one person? The righteousness of God is the righteousness of the relationship of Father, Son, and Spirit. They are faithful in those relationships; they are just in those relationships. Those relationships have the characteristic of righteousness. And this is active righteousness; this isn’t simply potential righteousness as a unitarian God would have.

Without the doctrine of the Trinity, we couldn’t claim that God is righteous in any meaningful way.

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3. The Trinity underscores the importance of relationships

In his book Traces of the Trinity, Leithart dives deep into a little-known theological concept called vestigia Trinitatis. Meaning “traces of the Trinity,” vestigia Trinitatis is all about identifying the Trinitarian underpinnings of a universe spoken into existence by a triune God.

In other words, if the Christian God is the creator of the universe, then it follows that there would be traces of the Trinity etched into the substructure of the cosmos—from the intricate complexities of science and mathematics to everyday human interactions.

By analyzing everything from the nature of time to human communication, Leithart follows many theologians before him in concluding:

The Father, Son, and Spirit live in a harmony and love that is a model for human life . . . . Others indwell our lives; therefore we ought to open our lives hospitably to them. We indwell the lives of others; therefore, we ought to see others not as obstacles to our plots and projects but as potential homes in which we can dwell together. A world of mutual [indwelling] implies an ethic of hospitality, welcome, invitation, companionship, centered on a common table.

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4. The Trinity demonstrates the true meaning of holiness

Likewise, our conception of holiness should be undergirded by a Trinitarian framework. To demonstrate this, Leithart first establishes the biblical understanding of holiness.

If we define holiness in biblical terms, holiness has to do with indwelling and possession. God consecrates persons and places and things by coming near to them and indwelling them in glory. God comes into the tabernacle and indwells the tabernacle. He is enthroned above the Cherubim in the most holy place, and he consecrates the tent by His presence. He claims places as his peculiar places by indwelling them in his glory.

Having shown the Bible’s unique take on holiness, Leithart goes on to explore its implications regarding the Trinity.

If that’s what holiness is about, if that’s what holiness means, then a single entity, a single person, a single divine person, cannot be holy. He can’t be holy in the sense that he is separated from everything. He can’t be holy in the sense that he consecrates or is consecrated by another.

But when we think about the Trinity as a holy communion, then we can see that indwelling is essential to their holiness. The Father is holy because he is indwelt by the Spirit and by the Son. The Son is holy because the Holy Spirit indwells Him eternally, the Holy Spirit that comes from the Father. The Spirit is holy because he is indwelt by the Father and the Son. The three persons consecrate each other in a communion of holiness.

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5. The Trinity clarifies the meaning of the “glory of God”

One of the most respected summaries of Christian doctrine, the Westminster Shorter Catechism, asserts “man’s chief end is to glorify God and to enjoy him forever.”

When some Christians hear that, their skin crawls. Doesn’t that make God seem selfish? Is the creator of the universe really that egotistical—really that insecure—that he has to create an entire species to satisfy his hunger for worship?

Leithart is sensitive to this objection—and says that a robust understanding of the Trinity can overcome it.

That objection comes from not recognizing that the God who seeks all glory for himself is not a single entity who is sucking the glory from everything, but a communion of persons, a communion of mutually glorifying persons. Jesus, at the beginning of his high priestly prayer, speaks of the glory with which the Father has glorified him, and he declares his intention to glorify the Father. Within the communion of God, the Father is not seeking glory from the Son; he is glorifying the Son. The Son is not seeking glory for himself, but he is seeking the glory of his Father. And the Spirit is not seeking glory for himself, but he is glorifying the Father and the Son, or he is the glory that glorifies the Father and the Son.

When we think about God as a God who glorifies himself within a Trinitarian context, we can see that there is a mutual glorification going on, and God is not selfish. No person of God is selfish. But within God, there is this humility and self-sacrifice for the sake and for the glory of the other.

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A practical doctrine

The doctrine of the Trinity can be daunting to describe, but its rewards are equally grand. When we glimpse the beauty of this teaching—not in spite of, but because of its rich complexity—its implications stretch before us in ever-widening circles: from the very reason for our existence, to the way we live our lives, to the way we treat one another, and even to the way we relate to other religions and worldviews.

Perhaps most precious of all, the doctrine of the Trinity reveals that woven into the very fabric of the universe is the self-giving love of God.

And what could be more practical than love?


Learn more about the Trinity, the sacraments, and hermeneutics straight from Peter Leithart himself. Learn more about the bundle and get it today! Free Bible Software. Priceless Insights. clickable image


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Written by
Taylor Jones
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Written by Taylor Jones