The Shorter Catechism Q and A 6.
Q. 6 How many persons are in the Godhead?
A. 6 There are three persons in the Godhead,-the Father, the Son, and the Holy Spirit; and these three are one God, the same in substance, equal in power and glory.
From the very beginning words of the bible we find the plural form of God-Elohim, as the Creator of all things, and yet the Spirit of Elohim hovered over the face of the waters, and it was the Word of Elohim which brought things into being (Genesis 1). “In the beginning God” (v. 1), finds some differentiation when we read that “the Spirit of God was hovering over the face of the waters” (v. 2). Just as God could have performed all this work in an instant, we could also read that this was done without the mention of the Spirit. Furthermore we also read, “then God said” (v. 3), when one assumes that creation could have also happened without the word being spoken. However, by this very revelation we understand that it was in fact through His Word that the whole of creation came into existence, a point which John in his gospel account echoes (1:1-3 Cf. Ps. 33:6, 9). As we proceed in the Genesis account we also find a reiteration of what we have already learned about God when He said, “Let Us make man in Our image” (Gen. 1:26).
God, His Spirit, and the Word, counseled together to create man in their image. From the very beginning words of scripture, we see that God is One in essence, but three in persons, equally engaged in the work of creation, but taking on their respective roles, nevertheless they together as “Us” and “Our” making humanity, male and female, in their image and likeness. Words like Deuteronomy 6:4; also from Moses, must therefore be understood as speaking to the shared substance of God, with all three persons having equal authority for us. For this reason the disciples did not question the baptismal formula of Jesus when He gave the Great Commission (Mt. 28:19). The apostle John brought these two key points together. “For there are three that bear witness in heaven: the Father, the Word, and the Holy Spirit; and these three are one” (I Jn. 5:7). At Jesus baptism we read that “the Holy Spirit descended in bodily form like a dove upon Him, and a voice came from heaven which said, ‘You are My beloved Son; in You I am well pleased’” (Lk. 3:22).