Two Reasons the Trinity Matters

Justin Dillehay:

How much does the Trinity matter to you? If you found out tomorrow that God is actually only one person instead of three, would your relationship with God feel any different? Would it require a drastic overhaul in the way you think or witness or pray? How much does the Trinity matter to you personally?

How much does the Trinity matter to your church? If you found out tomorrow that your beloved youth pastor had become a staunch modalist—he now insists the Father, Son, and Spirit are actually one person in three manifestations instead of three distinct persons—would your church excommunicate him? Or would that seem like splitting hairs? Is the Athanasian Creed really right to say, “Whoever wishes to be saved must think thus of the Trinity. And whoever rejects this faith will perish everlastingly”? Or is that the overstatement of the millennium?

Judging by the church’s historic creeds, Christians used to think the Trinity is really important. Judging by the honest answers likely given to the questions above, many modern Christians have lost the sense of why it’s so important, even if they’ve retained it in their doctrinal statements. But judging by a growing number of voices, there’s a renewed sense we’ve lost something precious that needs to be recovered.

Most of us have retained a formal belief in the Trinity. What we need to recover is an understanding and a felt sense of why it matters so much. To help us do that, here are two reasons why the Trinity matters.

1. The Trinity Matters because the Gospel Matters

The Trinity isn’t some complicated distraction from the simple gospel—it’s actually part of the gospel. Now, as Fred Sanders once quipped, this doesn’t mean you should begin every witnessing encounter, “God loves you and has a wonderful Trinity for you to understand.” You don’t have to unpack the Trinity in every gospel presentation (although you might, especially if you’re talking to a Muslim).

Nevertheless, I would maintain that the Holy Trinity is right below the surface in even the simplest gospel presentation (and it may poke its head up now and then).

If you don’t believe me—if you still think the Trinity is just advanced theology for the experts—consider John 3:16, one of the most famous and simple gospel statements in the whole New Testament. And think carefully about what it says: “For God so loved the world that he gave his only begotten Son, that whoever believes in him should not perish, but have eternal life.”

Did you ever notice that even in John 3:16 you’re already wading into trinitarian waters? Don’t get me wrong—I’m not saying that the whole doctrine is here full-blown (you’ll need the rest of John’s Gospel to get the Holy Spirit, including a few verses earlier in 3:5). But just think about all the Trinity-related truths stated or implied in this one simple verse. I can think of at least six:

  1. Two of the three persons are explicitly mentioned: God and his only begotten Son.
  2. The fact that God has a Son tells us that he’s a Father. It also suggests that when Scripture speaks simply of “God,” it’s often referring specifically to the Father.
  3. The fact that the Father gave his Son tells us they’re distinct persons. The Father can’t be the Son if he gave the Son.
  4. It says something about how the Father loves his Son that giving him would be the ultimate demonstration of his fatherly love.
  5. The fact that Jesus is referred to as God’s only Son suggests there’s something unique about Jesus’s sonship. After all, Scripture teaches that God has other sons (Job 2:1Heb. 2:10). In fact, John has already told us in 1:13 that when we believe in Jesus, we become God’s children. So how can he say that Jesus is God’s only Son? Answer: because while we are sons by grace, he is Son by nature. We become God’s sons by adoption and regeneration, but he doesn’t become God’s Son—he simply is God’s Son, begotten from the Father before all worlds, God from God, light from light, begotten and not made.
  6. John 3:16 tells us that this is how we receive eternal life—by the Father giving his Son. Salvation is trinitarian. The Father has an only, eternally begotten Son, and in his love for sinners he sends that Son for us. The Son of God becomes a Son of Man, so that the sons of men might become sons of God. And then, the Father and Son send their Spirit to to dwell in us so we can experience this new life as sons (John 3:57:37–3915:2616:12–15).

As Paul puts it in Galatians 4,

But when the fullness of time had come, God sent forth his Son, born of woman, born under the law, to redeem those who were under the law, so that we might receive adoption as sons. And because you are sons, God has sent the Spirit of his Son into our hearts, crying, “Abba! Father!” (Gal. 4:4–6)

As one writer has said, “The Trinity and the gospel have the same shape.” Are you beginning to see why? This is how God saves us—by sending his Son and Spirit. Our salvation hangs on these two sendings. Without them, God would still be a Father, but he wouldn’t be our Father. He would still have a Son, but he wouldn’t have many sons.

The Trinity matters because the gospel matters.

2. The Trinity Matter because God Matters

The Trinity matters because this is who God is. It’s who he always was and would’ve been even if there had been no you, no me, and no heavens and earth. The question isn’t first and foremost, “Is this practical?” or “Will this be on the test?” The question is “Do I want to know God?” As Fred Sanders observes,

It makes no sense to ask what the point of the Trinity is or what purpose the Trinity serves. The Trinity isn’t for anything beyond itself, because the Trinity is God. God is God in this way: God’s way of being God is to be Father, Son, and Holy Spirit simultaneously from all eternity, perfectly complete in a triune fellowship of love. If we don’t take this as our starting point, everything we say about the practical relevance of the Trinity could lead to one colossal misunderstanding: thinking of God the Trinity as a means to some other end, as if God were the Trinity in order to make himself useful.

One reason we Americans neglect the Trinity is because we’re so pragmatic. Instead of asking “Is it true?” we’re more likely to ask “Is it useful?” “Will it help me get ahead?” “Will it make me a better spouse or parent?” Those are good questions, but if that’s all that matters to us, then how are we any different from the pagans? Even the pagans care about those things.

The number one question is, “Do you want to know God?” Because as Jesus said, “This is eternal life: that they know you the only God and Jesus Christ whom you have sent” (John 17:3).

To know God savingly is to know him as Father, Son, and Holy Spirit. Anything less is sub-Christian. The Trinity matters because God matters, even if it doesn’t strike us as practical.

And yet it is practical.

Because—to bring our two points together—the kind of God we have determines the kind of relationship we will have with him.

For example: Is your God an all-sufficient fountain of joy and love with an inexhaustible supply available for you anytime? Or did your God create you and save you because he was lonely and needed you? It depends. Is your God the unitarian God of Arianism (think Mormons and Jehovah’s Witnesses), modalism, or Islam? Or is he the biblical three-in-one? The God of John’s Gospel was never lonely, because even in the beginning, before anything made was made, he already had someone with him. “The Word was with God” (John 1:1).

This is good news, because it tells us God didn’t create us because he needed somebody to love. He wasn’t without family. He was already a Father. And he already had an eternally begotten Son, the radiance of his glory and the exact imprint of his nature (Heb. 1:3), lying in his bosom (John 1:18) and basking in his love (John 17:24). You and I aren’t the result of some man-shaped hole in the Father’s heart; rather, you and I represent the overflow of the Father’s eternal love for his Son—as though the Father had said, “Son, this love of ours is just too good to keep to ourselves. So together with our eternal Spirit, let us make man in our own image, so that others might see and experience our love, and so that you might be the firstborn among many brothers” (cf. Gen. 1:26Rom. 8:29).

Is the Trinity practical? Let me ask you—what kind of salvation does your gospel give you? A judge who forgives your sins? Not bad. But not good enough. The triune gospel is better by far. It’s God giving himself to you in creation and redemption. The same Son who was begotten by the Father before all worlds was sent by the Father into this world, to live and die for us and our salvation. And the same Spirit who proceeded from the Father and the Son from all eternity was sent by the Father and the Son into this world, to live inside us and bring us to Christ—and through Christ to the Father—so that we might be taken into his family, surrounded by his life and love, to glorify and enjoy him forever.

It’s more than forgiveness. It’s joining an eternal family. It’s being conformed to the image of the Son by the Spirit (Rom. 8:29) and becoming a partaker of the divine nature (2 Pet. 1:4). In short, it’s the kind of salvation that only the trinitarian God can offer.

This is the Holy Trinity. This isn’t just a doctrine; this is our life. It’s more than just a mystery or a mind-bending math problem; this is our God, who loves and gave his Son for us (John 3:16), who loves us and gave himself for us (Gal. 2:20), who loves us and lives inside of us (Rom. 5:5).

Peter serves as a pastor-teacher, at home and abroad, resourcing gospel-centred communities.