The Foundations · Doctrine of God
The Nicene Trinity
One God in three Persons — Father, Son, and Holy Spirit.
The doctrine of the Trinity is the Christian confession that the one God eternally exists as three co-equal, co-eternal Persons: the Father, the Son, and the Holy Spirit. This is not three gods, and it is not one Person wearing three masks. It is the mystery at the heart of Christian worship, prayer, and salvation, confessed most clearly at the Councils of Nicaea (325) and Constantinople (381).
One God
Christianity inherits from Israel the confession that God is one (Deuteronomy 6:4). There is one divine essence, one uncreated, eternal, all-powerful, all-knowing, and all-good Being. Whatever it means to be God, God is that fully, simply, and without division.
Three Persons
The New Testament reveals this one God as Father, Son, and Holy Spirit. The Father sends the Son; the Son becomes incarnate, dies, and rises; the Spirit is poured out on the Church. Each is addressed, worshipped, and prayed to as God, and yet they are distinct — the Father is not the Son, the Son is not the Spirit, the Spirit is not the Father.
Consubstantial (homoousios)
At Nicaea (325), the Church confessed that the Son is homoousios — of the same substance — with the Father. He is not a creature, not a lesser divinity, not made in time. He is 'God from God, Light from Light, true God from true God, begotten, not made, of one essence with the Father.'
At Constantinople (381), the same confession was extended to the Holy Spirit, 'the Lord and Giver of Life, who proceeds from the Father, who with the Father and the Son together is worshipped and glorified.'
Why it matters
The Trinity is not a puzzle bolted on to Christianity — it is Christianity. If the Son is not truly God, he cannot save. If the Spirit is not truly God, he cannot make us sharers in the divine life. Christian worship, baptism, and prayer are all Trinitarian: we are baptised into the name of the Father and of the Son and of the Holy Spirit (Matthew 28:19).
“We believe in one God, the Father almighty… and in one Lord Jesus Christ… consubstantial with the Father.”
“The Godhead of the Father and of the Son and of the Holy Ghost is all one, the glory equal, the majesty co-eternal.”