When was the last time you heard a sermon or read a book on God’s triunity? When is the last time you spoke of God’s triunity in a counseling context? I know what some of you are thinking: “You must be joking! The doctrine of God’s triunity is far too complex, esoteric, and impractical.” But is it really?
God is Triune
According to Fred Sanders, “The doctrine of the Trinity stands or falls with the right understanding of the relations in God.”1Fred Sanders, The Triune God (Grand Rapids, MI: Zondervan, 2016), 35. This means we must be careful to distinguish between the one divine essence (or substance) and the eternal relations that each of the three persons has with the others in God. These relations were made known in the “missions” of the Son and the Spirit. Paul tells us that “when the fullness of time had come, God sent forth his Son” (Galatians 4:4). He was “born of woman” (His incarnation) and “born under the law” (His mediation). By fulfilling God’s law and satisfying God’s justice, He redeemed us from slavery and secured our “adoption as sons” (v. 5). Paul doesn’t stop there, but adds, “God has sent the Spirit of his Son into our hearts, crying, ‘Abba! Father!’” (v. 6). In other words, the Spirit seals to us what the Son accomplished for us.
These “sendings” of the Son and the Spirit into the world are extremely significant because they reveal that God’s life takes place in eternal relations of origin. God behaves as Father, Son, and Spirit in redeeming us because He is eternally Father, Son, and Spirit. In other words, the “sendings” reveal eternal processions (John 8:42; 15:26).2These eternal processions are not chronological or ontological, but personal (relational). Sanders explains, “The Son is sent to be incarnate because He stands in an eternal relation of origin with regard to the Father, a relation called generation or begetting; and the Spirit is poured out because He stands in an eternal relation of origin with regard to the Father, a relation called spiration or breathing-out.”3Sanders, Triune God, 112–13.
God is Love
When we speak of God’s triunity, we aren’t being academically picky or theologically fussy; rather, we’re proclaiming the heart of the Christian faith. We confess it in the Apostle’s Creed and when we’re baptized in the name of the Father and of the Son and of the Holy Spirit (Matthew 28:19). Moreover, when we speak of God’s triunity, we’re affirming that He is love (1 John 4:8). As C. S. Lewis observes, “All sorts of people are fond of repeating the Christian statement that ‘God is love.’ But they seem not to notice that the words ‘God is love’ have no real meaning unless God contains at least two persons. Love is something that one person has for another person. If God was a single person, then before the world was made, He was not love.”4C. S. Lewis, Mere Christianity (San Francisco, CA: Harper, 2015), 160. All that to say, God is love because He is eternally Father, Son, and Spirit.
Why did the Father send the Son into this world? “O righteous Father, even though the world does not know you, I know you, and these know that you have sent me. I made known to them your name, and I will continue to make it known, that the love with which you have loved me may be in them, and I in them” (John 17:25–26). The Son is the object of the Father’s eternal love. Christ prays that this same love might be in us. Michael Reeves explains, “The Father so delights in His eternal love for the Son that He desires to share it with all who will believe. Ultimately, the Father sent the Son because the Father so loved the Son—and wanted to share that love and fellowship.”5Michael Reeves, Delighting in the Trinity: An Introduction to the Christian Faith (Downers Grove, IL: InterVarsity Press, 2012), 70. The mission of the triune God, therefore, is an overflow of His love. It is by the Spirit that the Father has eternally loved His Son (Matthew 3:16–17). By sharing the Spirit with us, the Father and the Son share their love with us.
The Father, the Son, and the Spirit dwell in an eternity of mutual delight. This means that God is satisfied in Himself. He doesn’t need to love us, nor does He need us to love Him. This is precisely the kind of love we need. We need someone to love us who doesn’t actually need us, and God has that kind of love in Himself. We don’t need to earn it. We don’t need to worry that it will change. We don’t need to worry that it’s contingent upon our performance. God triune lavishes His love upon us, meaning the Father loves us, the Son reveals the Father’s love, and the Spirit assures us of the Father’s love (Romans 5:5; Galatians 4:6; Titus 3:4–7). What could be more practical than that?