The Scriptures in many instances and in many ways tell us that God is uniquely one. Both in the Old Testament and in the New, there are many passages which declare this. We select here just a few:
First Corinthians 8:4: "There is no God but one."
Isaiah 45:5: "I am Jehovah and there is no one else;/Besides Me there is no God." In verses 6, 21, and 22; 46:9; and 44:6, 8, we also find the same words.
In these passages God repeatedly says, "There is no God besides Me." He does not say, "There is no God besides us," but, "There is no God besides Me." "Me" is singular, only one. These repeated declarations of God strongly prove that God is uniquely one.
Psalm 86:10: "Thou art God alone." Here it does not say, "Ye are God alone," but, "Thou art God alone." This also proves that God is only one. It is "Thou," not many, as would be signified by "Ye."
That God is one is a clear and definite revelation of the Scriptures. But in Christianity, besides this orthodox teaching or interpretation, which is based on the clearly stated revelation of the Scriptures, some say that there are three Gods—the Father is one God, the Son is one God, and the Spirit also is one God, and these three become one corporate God. Individually speaking, they say, there are three Gods; corporately speaking there is one.
Others say that there are two Gods—the Father is one, and the Son also is one, but the Spirit is not, because the Father has His person and the Son also has His person, but the Spirit is only a power, a means, just like electricity, and has no person.
Such statements concerning the existence of three Gods or two Gods are contradictory to the fundamental revelation of the Scriptures; therefore, we should not accept them. We must stand absolutely on the scriptural revelation and believe that God is one.
(Concerning the Triune God—the Father, the Son, and the Spirit, Chapter 1, by Witness Lee)