It is a word which did not even exist at that time. The word trinity is in fact a theological term adopted later by Christians to define what the Bible teaches concerning God. To correspond with Biblical revelation, the Christian must equally emphasize that God is one and three. Though God is immensely complex, and cannot be exhaustively known, He has so revealed Himself in scripture that He can be truly known . That there is only one God, yet that the One God is Father, Son and Holy Spirit is the most basic Christian belief.
All Christian beliefs depend upon the truth of that single statement.
The word trinity is simply used to express what the Scriptures delineates as God comprised of three, who are infinite, personal, in complete unity of will, purpose, action and love, yet cannot be separated though they have different functions. The Scriptures speak of God the Father who is the co-Creator with God the Son, and God the Holy Spirit. From the above study, it is clear that Christians have always believed in One God. Yet, the Bible tells us that this One God has acted in history, showing Himself to be God the Father, God the Son and God the Holy Spirit. As we mentioned earlier, the word Trinity is shorthand for the concept of three and one.