From the beginning of creation Holy Trinity is at work. "Spirit of God" was hovering over the face of waters. Then God said, "Let there be light, and there was light". The creation is done by the Father through His word (In. 1 :3) and His Spirit (Gen. 1: 1-4). Concerning man's creation, God says, "Let us make man in our image, according to our likeness" 0/. 26). When Isaiah saw the glory of God in the temple, he cried out "Holy, Holy, Holy". Three fold 'Holy' cold refer to the three persons of Trinity. In Aaronic benediction "The Lord" is repeated thrice (Num.6:24-26).
In the NT, the Holy Trinity is revealed during the baptism of Jesus. "He saw the Spirit of God descending like a dove and alighting upon him. And suddenly a voice came from Heaven, "This is my beloved Son" in whom I am pleased (Mt. 3:16-17). While teaching the Apostles Jesus says, "But the Helper The Holy Spirit whom the Father will send in My Name, he will teach you ..... " (In. 14:26). The
Baptismal formulae of the early church reveals the doctrine of Trinity. "Go therefore, and make disciples of all nations, baptizing them in the name of the Father, of the Son and of the Holy Spirit" (M1. 28:19). The Apostolic benediction was in the name of Trinity. "The grace of the Lord Jesus Christ, the love of God, and the fellowship of the Holy Spirit be with you all. Amen" (2 Cor. 13:14). The Apostolic teaching also bear witness to the doctrine of Trinity. "But when the fullness of time had come, God sent forth His Son ... God has sent forth the Spirit of His Son into your hearts, crying out, "Abba, Father" (Gal. 4:4-6).