It is the testimony of both the Old and New Testaments and of the Christian Church that God is both One and Triune. The biblical revelation testifies that there is only one God and that He is eternally existent in three persons—Father, Son, and Holy Spirit.
God the Father
God the Father is the creator and sustainer of all things, and He created the universe in love. He created man in His own image for fellowship and called man back to Himself through Christ after the rebellion and fall of man.
Jesus Christ is eternally God. He was together with the Father and the Holy Spirit from the beginning, and through Him, all things were made. For man’s redemption, He left heaven and became incarnate by the Holy Spirit through the virgin Mary; henceforth, He is forever one Christ with two natures—God and man—in one person.
The Holy Spirit
The Holy Spirit is God, the Lord, and giver of life, who was active in the Old Testament and given to the Church in fullness at Pentecost. He empowers the saints for service and witness, cleanses man from the old nature,
and conforms us to the image of Christ. The baptism in the Holy Spirit, subsequent to conversion, releases the fullness of the Spirit and is evidenced by the fruits and gifts of the Holy Spirit.