John Stott cites scriptural authority for the Trinity in the baptism of Jesus and the Great Commission (Matt.3:17; 28:19). Also 1 Pet.1:2; 2 Cor.13:14. He lists three approaches to the truth of the Trinity.

First, there is the approach of history. It was a gradual unfolding historical revelation. It was the facts of the observation of the apostles about Jesus, his teaching and miracles and his speaking of God as his Father, and the Comforter or Spirit of Truth who would take his place after he left them, which compelled them to believe in the Trinity.

Secondly, there is the approach of theology. The major problem felt by the early church fathers was how they could reconcile the unity of God with both the deity and the distinctness of Jesus, or how they could believe that Jesus was both divine and distinct from the Father without committing themselves to two Gods. All of them began with the unity of God (Deut.6:4). They failed to define the nature of God’s unity. Not mathematical but organic. Within the complex mystery of the infinite God are three eternally distinct personal modes of being.

Thirdly, there is the approach of experience. There are many things in life which we cannot fully explain, but nevertheless experience e.g. electricity, barometric pressure, or love. Every time we pray we enjoy access to the Father through the Son by the Spirit (Eph.2:18).[1]

In his commentary on Ephesians he discerned a trinitarian structure.

As we continue to compare the two halves of Ephesians 1, another feature of them strikes us: both are essentially Trinitarian. For both are addressed to God the Father, the benediction to ‘the God and Father of our Lord Jesus Christ’ (verse 3) and the intercession to ‘the God of our Lord Jesus Christ’ (verse 17), who is also called ‘the Father of glory’ or (NEB) ‘the all-glorious Father’. Next, both refer specifically to God’s work in and through Christ, for on the one hand he ‘has blessed us in Christ’ (verse 3) and on the other he ‘accomplished in Christ’ a mighty act of power when he resurrected and enthroned him (verse 20). And thirdly both sections of the chapter allude – even if obliquely – to the work of the Holy Spirit, since the blessings God bestows on us in Christ are ‘spiritual’ blessings (verse 3), and it is only ‘by a spirit (or Spirit) of wisdom and revelation’ that we can come to know them (verse 17). I do not think it far-fetched to discern this Trinitarian structure. Christian faith and Christian life are both fundamentally Trinitarian. And the one is a response to the other. It is because the Father has approached us in blessing through the Son and by the Spirit that we approach him in prayer through the Son and by the Spirit also (cf.2:18).[2]

In the Lord’s Prayer he saw a trinitarian exposition.

a trinitarian Christian is bound to see in these three petitions a veiled allusion to the three persons of the Trinity, since it is through the Father’s creation and providence that we receive our daily bread, through the Son’s atoning death that we receive the forgiveness of our sins, and through the Holy Spirit’s indwelling power that we can be rescued from the evil one.”[3]

(Ted Schroder, JOHN STOTT A SUMMARY OF HIS TEACHING, Piquant, 2021, pp.7,8.)

[1] John Stott, Christian Basics, Hodder & Stoughton, 1991

[2] John Stott, God’s New Society, 52, InterVarsity Press, 1979

[3] John Stott, Through the Bible, Through the Year, 205, Monarch Books, Lion Hudson, 2014