For the prayer which He has taught us suits, as we have proved, none but the Creator. It is, of course, another matter if He does not wish to be prayed to, because He is the supremely and spontaneously good God! But who is this good God? There is, He says, “none but one.” It is not as if He had shown us that one of two gods was the supremely good; but He expressly asserts that there is one only good God, who is the only good, because He is the only God.
Tertullian
The Five Books Against Marcion, Book IV
Chapter XXXVI