Yet the Bible also clearly teaches that there is a plurality of “Persons” that make up the Godhead (Genesis 1:1 , 26; 11:7; Matthew 28:19 ). In many places the Bible calls the Father, God; the Son, God; and the Holy Spirit, God. (Genesis 1:1 , 26; 11:7; Matthew 3:16-17 ; 28:19; 2 Corinthians 13:14) And yet there can’t be three gods because Scripture is clear: there is only one God. We have to give equal weight to the texts of Scripture that declare God to be one and also to the texts that reveal the Father, the Son and the Holy Spirit to be God as well. Since we believe Scripture cannot contradict itself, to resolve (or explain this mystery clearly spoken of in Scripture) we use the word, “Trinity.” Trinity is simply a word the church uses to speak of how God reveals Himself to us in Scripture. Perhaps we could say, there is “one what” and “three who’s”.
That said, we also believe that these three “Persons” are of the same essence or substance and power - in other words each are and can rightly be called “God.” By the word “Person” we simply mean that the Father, Son and Holy Spirit are not a part or a quality in each other, but that which subsists of itself.
“One substance” is what the three persons are in common, and what no one else is. God is one in substance. In other words, there is no division of God. The Father is not one third God or part of God; the Father is God. The same is true of the Son and the Spirit. All three persons share in the divine substance. They are equally, truly and fully God. In other words, they’re all the same God. There is one God, one divine substance.