There is One God
“The object of our worship is the One God” (Tertullian: Apology, xvii). A characteristic teaching of the Christian faith from the beginning was that there is one God. In this respect, Christian teaching mirrored Jewish belief as opposed to pagan concepts of the time.
All who bore the name of Christ recognized this fact, and even when Trinitarian ideas had taken hold, the basic concept of One God was always declared. The inconsistency between monotheism and the doctrine of the Trinity, obvious to Jews and perhaps to pagans, was not admitted by trinitarians.
While exalted by many denominations today, the trinitarian concept was not part of the original gospel and took some time to develop in the early church. It began with confused ideas about the nature of Christ and his eternal relationship with the Father.
The Second Century
The Epistle of Barnabas speaks at length of the work and atoning sacrifice of Christ, and the author’s teaching appears to be scriptural.
Irenaeus makes some statements that are bold and true: “He created all things, since he is the only God, the only Lord, the only Creator, the only Father, alone containing all things, and Himself commanding all things into existence” (Against Heresies, II, i).
“The Father Himself is alone called God … the Scriptures acknowledge Him alone as God” (II, xxviii.4). “These (the apostles) have all declared to us that there is one God, Creator of heaven and earth, announced by the law and the prophets; and one Christ, the Son of God” (III, i, 2). “Neither the prophets, nor the apostles, nor the Lord Jesus Christ in His own person, did acknowledge any other Lord or God, but the God and Lord supreme … and the Lord himself handing down to his disciples, that He, the Father, is the only God and Lord, who alone is God and ruler of all” (III, ix, 1).
“Such, then, are the first principles of the Gospel; that there is one God, the Maker of the universe; He who was so announced by the prophets, and who by Moses set forth the dispensation of the law, which proclaim the Father of our Lord Jesus Christ, and ignore any other God or Father except Him” (III, xi, 7).
Such clear declarations of the unity of God would seem to leave no room for trinitarian teaching, and indeed, that dogma had certainly not been formulated when Irenaeus wrote late in the second century.
It is very important to emphasize that the doctrine of the Trinity is foreign to New Testament teaching. It is not simply that the word “Trinity” and the phrases “God the Son” and “God the Holy Spirit” are nowhere used in the Bible (which, of itself means nothing), but the fact that the very concept of God as ‘three in one’ is never found in the Scriptures (God is always described absolutely as ‘one’, never ‘three in one’). As illustrated by the following quotations, trinitarian teaching developed slowly as a result of attempts to adapt Christian theology to ideas current in the Greek philosophical systems. The attempts began with ideas relating to the personal pre-existence of Christ.