Doctrine of the Trinity

The Christian Gospels speak of God the Father, God the Son, and God the Holy Spirit (or God the Holy Ghost, to use the language of the Authorised Version of the Bible and the Book of Common Prayer). For example, Jesus promises his followers that his Father will send them the Holy Spirit, 'the Comforter, who will teach them all things' (John 14, 26); in the garden of Gethsemane, he prays to his Father that he might be spared the ordeal of crucifixion (Matthew 26, 39; Mark 14, 35-36; Luke 22, 42); questioned by the Jewish high priest Caiaphas, he acknowledges that he is the Son of God (Matthew 26, 63-64; Mark 14, 61-62; Luke 22, 70); and when after the crucifixion he appears to his followers, he instructs them to baptise converts 'in the name of the Father, and of the Son, and of the Holy Spirit' (Matthew 28, 19).

Christians recognise the distinctness of God the Father, God the Son, and God the Holy Spirit, as the Gospel narrative requires, but nonetheless believe that there is one God; and so the first Christian theologians, who had the task of formulating a systematic account of Christian belief, needed to clarify the relationship between God the Father, God the Son, and God the Holy Spirit, and to do so in a way which explains how despite their distinctness they are a single God. The generally accepted account, which became the orthodox doctrine and is usually referred to as the doctrine of the Trinity, is that God the Father, God the Son, and God the Holy Spirit are three 'persons' but one 'substance'. (As the Athanasian Creed puts it, 'we worship one God in Trinity, and Trinity in Unity, neither confounding the persons, nor dividing the substance'.) However, this statement of the doctrine can, as it stands, easily mislead. Neither the word 'person' nor the word 'substance' have their usual meanings in English, both being translations of Greek philosophical terms: 'person' translates ὑπόστασις (hupostasis), which in this context means 'actual existence' or 'reality', and 'substance' translates οὐσία (ousia), which in this context means 'nature' or 'essence'. It would therefore be better, but still not very illuminating, to say that according to the doctrine of the Trinity God the Father, God the Son, and God the Holy Spirit are three 'realities' which have the same nature or essence. However, whatever the precise import of the doctrine, it is clear that those who formulated it intended to emphasise that the three 'persons' of the Trinity have always existed together, the existence of the one being inseparable from the existence of the others, and that they have equal status. As the Athanasian creed puts it, 'the Godhead of the Father, of the Son, and of the Holy Ghost, is all one: the Glory equal, the Majesty co-eternal. Such as the Father is, such is the Son:and such is the Holy Ghost'.

Many of the earliest Christian doctrines to be regarded as heresies were condemned because they conflicted in one way or another with the doctrine of the Trinity. See Arianism and Monothelitism.