On the Sunday after Pentecost, the Church celebrates the Feast of the Holy Trinity. The Trinity has been called the central doctrine of Christianity, yet if you asked most Christians to explain the Trinity, most would respond with vague metaphors, or would stumble over incomplete doctrinal statements.
Christians believe in one God. God has one divine nature, but is three persons. Now “persons” in this instance means something different than the usual definition of a person. In the Trinity, the Father, Son, and Holy Spirit are all instances of the same divine nature. Sometimes my Muslim friends struggle to believe that we Christians are monotheists, but truly, we are. Some theologians have said that the “what” of God is a single divinity, which the “who” of God is Father, Son, and Holy Spirit.
The word Trinity doesn’t appear anywhere in the Bible. Nevertheless, there are many references in the Scriptures that help us define the Trinity. At the end of Matthew’s Gospel contains the command: “Go forth to all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Spirit.” In the Second letter to the Corinthians, Paul writes, “”The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all.” And the beginning of John’s Gospel illustrates the idea of the unity of God, saying both that Jesus “was” God, and “was with” God.
It’s never adequate to simply think of the persons of the Trinity with mere functional labels like Creator, Redeemer, and Sanctifier. While those labels are accurate enough, they lack any sense of relationality within the Trinity. The Trinity is primarily about the loving relationship at the heart of God’s essence. The passages of John’s Gospel that we read during the Easter season go to great lengths to describe this relational love. To separate the Trinity into functional roles is called Modalism, and it misses an important point: The idea of the Trinity is our attempt to describe God’s essence, and God is essentially relational. The Love within God is expressed in ways that mirror God’s trinitarian nature.
The challenge for theologians– and all Christians– is that we struggle to talk about God’s infinite, loving, relational essence with finite human language, and that language will always be imperfect. My Muslim dialogue partners struggle to express God’s nature with 100 names; we’re trying to do it with three. Ultimately that understanding of God is a mystery whose full revelation awaits us in God’ Kingdom.