“There is one and only one God, eternally existing and fully expressed in three Persons, the Father the Son, and the Holy Spirit.. Each member of the Godhead is equally God , each is eternally God, and each is fully God – not three gods but three Persons of the one Godhead. Each Person is equal in essence as each possesses fully the identically same, eternal divine nature. Yet each is also an eternal and distinct personal expression of the one undivided divine nature. The Holy Spirit then is fully God. He is not one third God, but fully God” Bruce Ware pg 103 in Father Son and Holy Spirit
Christians do not believe that there are ‘three gods in one’ but do believe that there are three persons all of the same substance, coequal, coexistent, coeternal, immutable forever.