Why Trinity?

“Most orthodox Christians claim to be “biblical” in doctrine yet also “Trinitarian”. Many share the view expressed by Whitely and by Kelly that the Pauline texts embody “traces of a Trinitarian ground-plan”. It is certainly the case that Paul unambiguously expresses the Christian belief in one God (1 Cor. 8:6), and that in many passages, both associations and distinctions are drawn between God as Father, Christ as Lord, and the Holy Spirit (Rom. 1:14; Rom 8:11, 14-16; Col. 1:15).

The Relation between Christ and the Holy Spirit has been discussed in numerous studies, and it cannot be claimed that Paul’s sentence “the Lord is the Spirit” (2 Cor. 3:17) contains an “is” of identity rather than meaning “is in the passage quoted…” In two successive reports of the Church of England Doctrine Commission (1987 & 1991), several of us argued that the origins of the doctrine of the Holy Trinity are to be found not in contingent factors arising from three centuries of historical and theological controversy, but in the Christian experience, shared by Paul and others, of being caught up “in a divine dialogue”, in which prayer is articulated by the Holy Spirit to God as Father through Christ as Lord (Rom. 8:14-17, 26-27). It is impossible to describe fully and explicitly the actuality of the situation of the believer and of the believing community and their relation to God without drawing on Trinitarian language.”

Anthony Thiselton, New Horizons in Hermeneutics, pg. 260