<P> Christian theologians believe that manifestations of the Trinity are made evident from the very beginning of the Bible . Genesis 1 : 1 - 3 posits God , His Spirit and the `` creative word of God '' 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 . </P>
when did the idea of the trinity start
Genesis 1 : 1 - 3 the 4th century