Note: Fred Sanders’s book The Deep Things of God: How the Trinity Changes Everything, prompted the following thoughts.
Evangelicals yearn for immediacy and practicality, not necessarily prolonged contemplation on the being, wonder, and glory of the triune God. We can agree, I think, that evangelicals are more likely to flock to a conference on parenting than a symposium on the Trinity. After all, most would ask, “What’s the payoff?”
Despite this pragmatic bent, evangelicals remain Trinitarian—they display a “tacit” Trinitarianism, according to Sanders (52). Using his thoughts as a framework, here are two reasons why Christians should care about the doctrine of the Trinity:
The Trinity = The Gospel
Christians should care about the Trinity because without the Trinity we have no gospel. The Bible unveils both the gospel of God and the God of the gospel—the surprising story of a God who aims to share the joy of his life with fallen sinners bent on their own self-destruction (Jn. 15:11). Yet whether we realize it or not, as soon as we begin talking about Jesus and salvation, we’re ushered into the “happy land of the Trinity” (68). How and why is this the case? It’s the case, because, as Sanders highlights, “The Trinity is the presupposition of the gospel” (25). This assertion is made plain when we call to mind that 1) the Father sent the Son to accomplish our redemption (Jn. 3:16) and 2) the Spirit applies the gospel to human hearts (Eph. 1:13–14).
Dipping into theological language, we need to see that soteriology (the doctrine of salvation) is grounded in the atonement of Christ, which is predicated upon the Son’s incarnation, which is a result of the Father sending his beloved Son on a rescue mission. Get it? Divine rescue, therefore, is “a Trinitarian affair.” And if our salvation is a Trinitarian affair, then we should tune in, sit up straight, move forward in our seats, and listen well: “God’s begetting [the Son] ought to have the tribute of our reverent silence.”
“Your God Is Too Small”
If the aim of good theology is to know and speak truly of God, then the doctrine of the Trinity should be of interest to every Christian because it guards against unworthy thoughts of God, which is the second reason Christians should care about the Trinity. In order to avoid unworthy thoughts of God, God must teach us about himself: “Leave man to guess God’s mind and purpose, and he will guess wrong; he can know it only by being told it.”
With these thoughts in place, consider the following statement: “God is Trinity primarily for himself and only secondarily for us” (80). Wait, what? What does that mean? The statement ushers us into the heart of a profound thought: God has a life of his own apart from our experience of him. Theologians refer to this as “the bliss of the Triune life.” Why “bliss”? Because God’s triune life is marked by joy. He is “blessed,” or “happy,” in himself (1 Tim. 1:11; 6:15).
What does this mean for us?
First, it means that creation wasn’t necessary. Sanders writes, “God minus creation would still be God” (75). God created the physical world because he chose to, not because he needed to. Theologian John Webster reminds us, “The act of creation is an act of God’s freedom.” Consequently, he “does not create in response to inner need or outer constraint and [he] could, without loss of perfection, refrain from creating.”
An entailment of the above reflection is that we do not exist by necessity. We continue to live, breathe, and have our being as a result of God’s sustaining grace, not because of our good eating and exercise habits—and certainly not as a result of brute willpower.
As with creation and our existence, so likewise with our salvation. God’s plan of salvation arose neither out of inner lack nor despairing loneliness. Rather, it was “according to the purpose of his will, to praise of his glorious grace” (Eph. 1:5–6). As one who is other-oriented by nature, God loves to share his life and joy with miserable sinners who deserve the opposite of mercy and grace.
These reflections guard against unworthy thoughts of God. In a memorable section of his book, he writes:
“The doctrine of the Trinity expels unworthy ideas about the perfection of God’s life. It is unworthy to think that God without us is lonely or bored. God is not looking for something to do in the happy land of the Trinity. God did not create the world in order to fill the drafty mansion of heaven with the pitter-patter of little feet. God is not pining away for companionship in a lonesome heaven” (100).
I think contemporary evangelicals are bothered by such thoughts. For some reason, the idea of a self-sufficient God rubs us the wrong way. Deep down we want God to need us. Therefore, I think Sanders’s observation is correct: “When evangelicals lose their sense of proportion, they begin to talk as if they no longer care about the character of God unless they get something from it” (75).
Self-centeredness mixed with pragmatism makes for a powerful combination. But we must resist it. Insofar as our theology is sourced and normed by Scripture, the appropriate reflex of the saints is to bend their thoughts and conceptions of God to his self-disclosure. Maintaining a robustly anti-speculative posture, we come with open hands, ready to receive what God has revealed about himself.
What we have (and need!) is an all-powerful, all-knowing, everywhere-present God who, out of perfect freedom, created all things (Gen. 1–2), sustains all things (Heb. 1:3), redeems rebellious sinners (Gal. 4:4–5), and purposes to unite all things in him (Eph. 1:10). To borrow a memorable line from Louis Berkhof (1873–1957), the God who exists is the God who is “not only independent in himself, but also causes everything to depend on him.”
This glorious triune God is the one from whom, to whom, and through whom are all things. “To him be glory forever. Amen” (Rom. 11:36).
In sum, the Trinity presupposes the gospel because the Bible discloses that God the Father sent God the Son to purchase salvation for his people and then indwell them by his Spirit. Additionally, the doctrine of the Trinity rules out unworthy thoughts of God by reminding us that he’s self-sufficient and fulfilled within himself. This ensures that the works of creation and redemption remain gratuitous acts of God and do not arise out of any imperfection in God’s inner life.
 Kevin J. Vanhoozer, Faith Speaking Understanding: Performing the Drama of Doctrine (Louisville: Westminster John Knox, 2014), 75.
 St. Gregory of Nazianzus, On God and Christ: The Five Theological Orations and Two Letters to Cleodonius, trans. Lionel Wickham (Crestwood, NY: St. Vladimir’s Seminary Press, 2002), 76. See more recently, Michael Allen, “Dogmatics as Ascetics,” in The Task of Dogmatics: Explorations in Theological Method, eds. Oliver D. Crisp and Fred Sanders (Grand Rapids, MI: Zondervan, 2017), 190–191.
 I love the way John Webster put it: “Theology is nothing other than an attempt to repeat the name which God gives to himself as he manifests himself with sovereign mercy, ‘I am the Lord, your Holy One (Isa. 43. 15).” See his Holiness (Grand Rapids: Eerdmans, 2003), 16–17.
 J. I. Packer, “Fundamentalism” and the Word of God (1958; Grand Rapids, MI: Eerdmans, 1990), 92.
 John Webster, “Creation out of Nothing,” in Christian Dogmatics: Reformed Theology for the Church Catholic, eds. Michael Allen and Scott R. Swain (Grand Rapids, MI: Baker Academic, 2016), 139.
 Timothy Keller, Prayer: Experiencing Awe and Intimacy with God (New York: Dutton, 2014), 68. Building upon Jonathan Edwards’s thoughts in The End for Which God Created the World, Keller notes that “the only reason God would have had for creating us was not to get the cosmic love and joy of relationship (because he already had that) but to share it.”
 Louis Berkhof, Systematic Theology (Grand Rapids, MI: Eerdmans, 1941), 58.