The Trinity

One God, three persons

The word ‘Trinity’ is not found in the Bible, but what it names runs all through it. Scripture insists first that God is one:

Hear, O Israel: The LORD our God, the LORD is One.

Deuteronomy 6:4

The New Testament never retracts this, yet it speaks of the Father, the Son and the Spirit each as God. "The Word was God" (John 1:1). Thomas answers the risen Jesus, "My Lord and my God!" (John 20:28). And Peter tells Ananias, who has lied to the Holy Spirit, "You have not lied to men, but to God!" (Acts 5:4). Yet the three are not one person under three names. At Jesus' baptism the Son comes up out of the water, the Spirit descends like a dove and the Father speaks from heaven (Matthew 3:16-17). The risen Lord then names all three together:

Therefore go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit,

Matthew 28:19

One name, three persons. Jerome, commenting on this verse, says the three are named at once because their Godhead is one, "to name this Trinity, being to name One God" Jerome. God is one; the Father, the Son and the Spirit are each God; the three are distinct. The doctrine of the Trinity is the refusal to let go of any of these. God is one in essence and three in persons. That is not one and three in the same respect, so it is no contradiction, though it is a mystery beyond our grasp.

How the church learned to say it

Tertullian, writing in Latin early in the third century, used the word trinitas and spoke of three persons of one substance Tertullian, Against Praxeas. The church's language grew more exact as it answered teachers who kept one truth by giving up another. Modalism guarded God's oneness by making Father, Son and Spirit three successive roles of a single person. Arianism guarded it by making the Son the first and highest of God's creatures. Tritheism, belief in three gods, fails in the opposite direction, against the Shema itself. Each tried to protect something true and lost something Scripture says.

The Council of Nicaea in 325 confessed that the Son is of one being with the Father. In the decades that followed, the Cappadocian Fathers, Basil the Great, Gregory of Nazianzus and Gregory of Nyssa, separated two Greek words that had often been used almost interchangeably: God is one ousia, one being, in three hypostases, three persons. The Council of Constantinople in 381 completed the Nicene Creed with its confession of the Holy Spirit, "who with the Father and the Son together is worshipped and glorified" Nicene Creed. The Athanasian Creed, which bears Athanasius's name but comes from the later Latin West, gives the classic rule:

And the catholic faith is this: that we worship one God in Trinity, and Trinity in Unity; neither confounding the Persons, nor dividing the Essence.

Athanasian Creed, 3

Where the churches differ

Orthodox, Catholic and Protestant churches confess the Trinity together in the words of the Nicene Creed. One phrase still divides East and West. The creed of 381 confessed that the Spirit proceeds from the Father, echoing Jesus' words about "the Spirit of truth who proceeds from the Father" (John 15:26). From about the sixth century Latin churches added ‘and the Son’, the filioque. The Catholic Church and most Protestant churches confess it, noting that the Spirit is called the Spirit of the Son and is sent by him. The Orthodox churches keep the original wording: the Father is the one source of the Son and the Spirit, and one part of the church should not have changed a creed confessed by the whole. Both confess the Spirit as fully God, worshipped with the Father and the Son.

The Trinity is not a puzzle for specialists but the shape of the Christian life: "For through Him we both have access to the Father by one Spirit" (Ephesians 2:18). Christians pray to the Father, through the Son, in the Spirit. See the lesson The Trinity and What is the Trinity?