‘Off with our shoes, please, for the Holy Trinity is holy ground. Away with figured syllogisms and ordinary arithmetic: here, logic and mathematics do not suffice. The need is rather for a listening ear, an obedient heart (Jn 7:17), rapt adoration, a careful engagement with the Holy Scriptures.’ (Prof Kenneth Grider, Christianity Today).

The doctrine of the Trinity has exercised the greatest Christian minds. Augustine was once walking along the seashore, deep in meditation on the Trinity, when he came across a small boy digging a trench in the sand. ‘What are you doing?’ he asked. ‘I want to empty the sea into this trench,’ came the reply. Augustine asked himself, ‘Am I trying to do the same thing as this child in seeking to exhaust with my reason the infinity of God and to collect it within the limits of my own mind?’

It is true that attempts have been made to find earth-bound analogies to the Trinity: body, soul and spirit; water, steam and ice; solids, liquids and gases. But all these are inadequate.

The word ‘Trinity’

The word trinity means ‘tri-unity’ or ‘three-in-oneness’. The word is not found in Scripture. As Warfield comments: ‘The doctrine of the Trinity is not so much heard as overheard in the statements of Scripture.’ Yet orthodoxy considers that the reader of God’s word is forced to conclude that (a) there is one God; (b) God is three persons; and (c) each person is fully God.

The word itself comes from Tertullian. He is said to have coined some 509 new nouns, 284 new adjectives, and 161 new verbs in Latin. Happily, not all of these caught on. But some of this terminology is reflected in expressions still used to define and explain the doctrine of the Trinity: (a) Trinity: this word was itself invented by Tertullian (b) Persona: this was introduced to translate the Greek word ‘hypostasis’; it is thought that in the expression ‘one substance, three persons’, Tertullian was trying to communicate the idea of a plurality of roles played by a single actor; (c) Substantia: this word expresses the fundamental unity within the Godhead.

In the Old Testament

A fundamental axiom of the OT is the unity of God, Deut 6:4. However, superimposed on this strict monotheism are hints of plurality: in the plural form ‘Elohim’; in the use of ‘us’ and ‘our’ as spoken by God; and in the personage of the ‘Angel of the Lord’. See Gen 1:26; 3:22; 11:7; 31:11-13; Psa 45:6-7 (cf Heb 1:8); Psa 110:1 (cf Mt 22:41-46); Isa 6:8; 48:16; 63:10; Hos 1:7; Mal 3:1-2.

In the New Testament

Again, in the New Testament the unity of God is everywhere assumed, 1 Cor 8:4; Eph 4:4, 6; Jam 2:19. But the threeness of God comes across repeatedly, as at our Lord’s baptism, Mar 1:9-11; and at the giving of The Great Commission, Mt 28:19. See also Jn 14:26 15:26 2 Co 13:14 Paul’s prayer, Eph 3:14-21; The upbuilding of the church, Eph 4:4-16; 1 Pe 1:2. The Annunciation, Lk 1:25-37.

‘One essence, three persons’

The relationship between the ‘oneness’ and the ‘threeness’ of God was formulated in the so-called Athanasian Creed. However, all such attempts to relate the unity and the threeness of God are approximations, and as such are open to criticism. Augustine wrote, ‘When one asks: What three? human speech suffers from a great lack of power. Nevertheless, we say: Three persons, not in order that we should say this, but that we should not be silent.’

Yet the term ‘person’ as applied to the Trinity is inadequate. It has come to denote for us self-conscious autonomy – a meaning which if applied to the Trinity comes perilously close to tritheism. There are not three individual personalities in God.

Father, Son and Spirit

The Father is first in order of manifestation, the beginning and source of all things, Gen 1:1. He is the fountain of all grace. He is the Father of the Lord Jesus Christ, Eph 3:14, of all people, as the source of their being and provider of their needs, and especially of the redeemed, whom he adopts as family members, with all the privileges, rights and duties which such membership implies, 1 Cor 6:17-18; 8:6; Eph 4:6; Lk 12:30, 32.

The Son is second in order of manifestation, the medium of all things, including creation and judgement, Jn 5:22. He is God manifested in the flesh, the saviour of the world, Act 5:31; 13:38.

The Son is often referred to as the one ‘through’ whom all things were created, Jn 1:3; 1 Cor 8:6; Col 1:16; Heb 1:2. The Son was an active agent in carrying out the plans and directions of God the Father.

The Spirit is third in order of manifestation, the divine agent who communicates, applies and seals the blessings of the Father and the Son to the redeemed, Eph 2:18. He is the helper and sanctifier of the redeemed, 1 Co 6:11; Gal 5:16.

The Holy Spirit’s activity in creation is often viewed as completing, filling, and giving life to all that God has made. Gen 1:2; Job 26:13; 33:4. The Heb. ‘ruach’ can mean ‘breath’, ‘wind’, or ‘spirit’, depending on the context.

The co-operation of the Trinity in redemption

This is illuminated in the following texts: Jn 1:1; 3:16; 17:3; Eph 1:1-14; Rom 8:32.

The resurrection of Jesus was a manfestation of Trinitarian power:-

1. The Father, Acts 2:23-24.
2. Jesus himself, Jn 2:19.
3. The Holy Spirit, 1 Pet 3:18.

All three persons of the Trinity have a hand in our justification; Rom 8:33; Acts 13:39; 1 Cor 6:11. ‘God the Father justifies, as he pronounces us righteous; God the Son justifies, as he imputes his righteousness to us; and God the Holy Ghost justifies, as he clears up our justification, and seals us up to the day of redemption.’ (Thomas Watson)