Now that I have written five thousand words about why I think the Christian doctrine of the Trinity is a true and biblical description of the One God, someone might wish to ask me, “What difference does it make?” Sure, traditional Christian orthodoxy (held today by evangelical and conservative Protestants of all denominations, traditional Roman Catholics, and most Eastern and Oriental Orthodox) believes in the Trinity, while Oneness Pentecostals, Jehovah’s Witnesses, Unitarians, liberals (both Protestant and Roman Catholic), and Muslims do not. But is that just an interesting and incidental detail, along the lines of different traditions of church decoration? Or is it relevant to how Christians live out their faith in practice? Does this Trinitarian theology matter?
I think it does matter, and it matters a lot. Now, I will readily grant up front that it does not seem to matter to many Christians, who live out their lives with scarcely a thought regarding Trinitarian vs. Unitarian doctrine. But I think it does matter, and ought to matter a great deal to Christian life and faith.
In the first place, worshiping Jesus is either obligatory or blasphemous. It can never be merely optional. If, as I have contended, Jesus is in fact God, then all creatures must in fact worship him as such. Jesus said, “Whoever does not honor the Son does not honor the Father, who sent him” (John 5:23). But if instead Jesus is not in fact God, then worshiping him is in fact idolatry, as Jews and Muslims allege. This is why the belief whether Jesus is God or not is the touchstone of true worship. If you get that wrong, then you are not worshiping God rightly.
But the divinity of Jesus is not a technicality which it is easy to get wrong. Jesus made very clear who he is. Unprejudiced readers of the Gospel accounts quickly understand who Jesus is claiming to be, whether they accept those claims or not. (All New Testament scholars, whether accepting or rejecting Jesus’s claims, are prejudiced readers from long before they earned their PhDs.) Jesus said, in many ways and at many times, that every person’s relationship to God the Father depends upon their relationship to him, to Jesus himself. If this claim is false, it is as preposterous as it is blasphemous. If it is true, as I have argued here, then it cannot be ignored.
The “three-ness” of God is more than just a detail relevant for correct worship, however. The loving, eternal relationships among the Father, the Son, and the Spirit provide the model for all redeemed relationships. Jesus repeatedly presents his relationship with the Father, even as God, as a model for redeemed humans’ relationships with Jesus and the Father. The unity of believers is predicated on the unity of the Father and the Son (John 17:11, 21). Jesus sends believers into the world just as the Father sent him into the world (John 17:18). Jesus will receive Christians eternally into his Father’s mansion to dwell with God forever (John 14:2-3). As the Father loved Jesus, so Jesus has loved his followers (John 15:10), and the Father himself loves Christians (John 16:27). Just as the Father and the Son are “in” each other (John 14:10-11; 17:21, 23), so Christians can be “in” God (John 14:20; 17:21) and the Holy Spirit will be “in” Christians (John 14:17). Jesus gives Christians the glory that he has from the Father (John 17:5, 22). No wonder, then, that Paul saw Christians as “heirs of God and co-heirs with Christ” (Romans 8:17), and offered the humility of the Son’s incarnation as a model for Christian humility (Philippians 2:1-11). No wonder that John spoke of all those who received Christ becoming (like him) children of God (John 1:12-13).
And because the relationships within God, among the Father, the Son, and the Holy Spirit, are the model for all redeemed relationships, they are a very practical illustration of the best that human relationships can aspire to. Human parents can love their children and glorify them as God the Father continually glorifies the Son. Children can honor their parents as God the Son continually honors his Father, and strives to make him known. The model for marriage relationships is Christ and the Church (Ephesians 5:22-33), which we have already seen Christ analogizing to his own relationship with the Father. Christian friendship is modeled on Christ’s love for his disciples: “Greater love has no one than this: to lay down one’s life for one’s friends.” (John 15:12-13). And this is another echo of the love between the Father and the Son. Nor are these sanctified relationships just up to us and our human effort, since the Holy Spirit lives in us, reminding us of this divine model and transforming our hearts into conformity with our divine Savior. Paul wrote, “Do not conform to the pattern of this world, but be transformed by the renewing of your mind” (Romans 12:2), and “these are the things God has revealed to us by his Spirit. The Spirit searches all things, even the deep things of God… But we have the mind of Christ” (1 Corinthians 2:10, 16). The more we understand the Trinity, the unifying love of the Father, the Son, and the Holy Spirit, the more all of our relationships will be transformed and redeemed. That is what I call practical and relevant!
Now, it is possible to hold an Arian or even adoptionist view of Jesus and think that God decided, for some unknown and arbitrary reason, to treat Christians in that same way. But it would be a decision, and it would be arbitrary, because there would be no real connection between Jesus and his followers, beyond the shared humanity. (And if you make the shared humanity the basis for Jesus’s relationship with God, then you are quickly stuck with a notion of universal salvation, which contradicts biblical teaching.) On the other hand, if there is a complex personal unity in the one God, then God is by nature loving, and those who have Jesus are inseparably connected to God’s love and life. The Trinity is the anchor of Christian security, as Jesus said, “I give [my sheep] eternal life, and they shall never perish; no one will snatch them out of my hand. My Father, who has given them to me, is greater than all; no one can snatch them out of my Father’s hand. I and the Father are one” (John 10:28-30). (Some readers may here recognize distant echoes of the formulations of John Zizioulas.) Redemption draws people in to relate to God and other people just as the divine persons relate to one another, in humble holy love.
In other words, the Trinity is not just an interesting fact about God. It is also our template for how to love today, and our blessed hope that we may one day, by grace transforming us into holiness, enter as fully as our created nature allows into Trinitarian life, and we may join the perfect community of the Father, the Son, and the Holy Spirit, who live and reign together, one God over all, now and forever.