Why write about the love and communion of the Trinity? Does the doctrine of the Trinity, which is often given little thought today, have any practical relevance for living the Christian life in our day?
The Trinity is a term used to describe the one true and eternal God that the New City Catechism summarizes well for us,
Q 3: "How many persons are there in God?"
A: "There are three persons in the one true and living God: The Father, the Son, and the Holy Spirit. They are the same in substance, equal in power and glory."
This is the teaching of the Bible: "For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one" (1 John 5:7).
We easily forget the basic New Testament teaching of Jesus that to be a Christian is to be one who is baptized "in the name of the Father and of the Son and of the Holy Spirit" (Matthew 28:19). To be a Christian is to belong to the Triune God. We were once alienated from God's family, strangers to Jesus Christ, and unable to live for or please Him. But now, because the Father loved us, He sent His Son into the world to save us, and together, they graciously sent the Spirit to give us new life in Christ so we could know what Paul knew: "The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit" (2 Corinthians 13:14). To become a believer is to be brought into communion with the Triune God—a reality far grander than we can ever fully grasp.
The doctrine of the Trinity may at first seem impractical and without relevance to everyday Christian living, but upon closer examination it is one of the most practical truths of all, for what can be more practical for the Christian than knowing God in Jesus Christ through the illumination of the Holy Spirit? This is the "eternal life" Jesus spoke of John 17:3, "And this is eternal life, that they know you, the only true God, and Jesus Christ whom you have sent." Jesus describes knowing Himself and knowing God the Father as eternal life. We were made to know God in all His glory, and the wonder of the gospel is that we can be restored to the knowledge of God, as Paul describes believers in Colossians 3:10 who "have put on the new self, which is being renewed in knowledge after the image of its creator." Simply put, the Trinity is the most practical of doctrines, because knowing God is eternal salvation and we cannot know God apart from who He is: Father, Son, and Spirit.
When God acts, He always acts as the Triune God. We see this clearly in creation and the incarnation. The Father creates all things: "In the beginning, God created the heavens and the earth" (Genesis 1:1) Yet, He creates all things through His Son: "All things were made through him, and without him was not any thing made that was made" (John 1:3). In Genesis 1:2, the Spirit, who gives life to all, also actively participated in creation, hovering over the face of the waters while the earth was still in its formless state.
We also see the Trinity at work in the gospel accounts of Scripture. When the Father sent His Son, the Son willingly came to bear our sins in the flesh. He was conceived in the womb of the virgin Mary by the power of the Holy Spirit. Likewise, in the resurrection, the Father raised the Son, and the Son came up out of the tomb, but He did so in the power of the Holy Spirit. Gregory of Nazianzus (329-390), an early Church Father, said of the Trinity, "I cannot think about the One without being instantly surrounded by the splendor of the Three, nor can I discern the Three without being immediately drawn back to the One." We understand there is mystery here, but it is the mystery of divine glory which leads us not to declare it irrational and impractical, but rather bring us to humbly adore and worship God Himself.
Communion with God is always fellowship with the whole Godhead. Yet there is a varied and distinct fellowship with the Father, with the Son, and with the Holy Spirit.
Scripture speaks of the love of the Father that flows to us through the Son and the Spirit. When John writes in 1 John 4:8, "God is love," it is the love of the Father he is speaking of, since he goes on to explain how this love comes to us: "that God sent his only Son into the world, so that we might live through him" (4:9). In the gospel, we see the love of God the Father on display. The Father is the one who sent His Son so that we should not perish but have everlasting life. Jesus Himself emphasized this to His disciples just before His death, "For the Father himself loves you, because you have loved me and have believed that I came from God" (John 16:27).
But the Fathers love doesn't exist apart from the Son, as Paul clarifies, "But God shows his love for us in that while we were still sinners, Christ died for us" (Romans 5:8). Paul also makes it clear that we do not experience the Father's love apart from the Holy Spirit. "And hope does not put us to shame, because God's love has been poured into our hearts through the Holy Spirit who has been given to us" (Romans 5:5).
At the heart of the Trinity is love and unity bringing us the gospel of saving grace: each person of the Godhead working in perfect and loving harmony and fellowship to justify, sanctify, and ultimately glorify sinners saved by God's amazing grace.
Just as we have been baptized into the name of the Father, the Son, and the Holy Spirit, we now enjoy loving communion with each person. We are loved with an everlasting love by the Father, reconciled by the Son, and are being transformed by the Spirit from one degree of glory to another.
May you through faith trust in the grace of the Lord Jesus Christ, experience the love of God, and delight in the fellowship of the Holy Spirit.