when did the idea of the trinity start
Trinity Christian theologians believe that manifestations of the Trinity are made evident from the very beginning of the Bible. Genesis 1:1-3 [12] posits God, His Spirit and the "creative word of God" [13] [14] together in the initial Genesis creation narrative account. While the Fathers of the Church saw Old Testament elements such as the appearance of three men to Abraham in Book of Genesis, chapter 18, as foreshadowings of the Trinity, it was the New Testament that they saw as a basis for developing the concept of the Trinity. One of the most influential of the New Testament texts seen as implying the teaching of the Trinity was Matthew 28:19, which mandated baptizing "in the name of the Father, and of the Son, and of the Holy Spirit". Another New Testament text pointing to the Trinity was John 1:1-14, in which the inter-relationships of the Triune God are reflected in the gospel author's description of "the Word", again showing the elements of the Triune God and their eternal (always was, always is, and always shall be) existence. (Revelation 1:8) Reflection, proclamation, and dialogue led to the formulation of the doctrine that was felt to correspond to the data in the Bible. The simplest outline of the doctrine was formulated in the 4th century, largely in terms of rejection of what was considered not to be consonant with general Christian belief. Further elaboration continued in the succeeding centuries.[15]
John 1:1 The phrase "the Word" (a translation of the Greek word "Logos") is widely interpreted as referring to Jesus, as indicated in other verses later in the same chapter.[4] This verse and others throughout Johannine literature connect the Christian understanding of Jesus to the philosophical idea of the Logos and the Hebrew Wisdom literature. They also set the stage for later understanding development of Trinitarian theology early in the post-biblical era.