The answer
If there were more than one God, it would be possible to compare among them; God would not have been absolute in His perfection. Also, if there were more than one God, God would not be ineffable, nor would it be impossible to describe His essence.
St. Clement of Alexandria insists, “God is one, and He is more than one, beyond unity.”352 And St. Athanasius of Alexandria finds the unity of God reflected in the order and harmony of the world. If there were many gods, the world would not be harmonious.
Some philosophers thought that there are many gods, they believed that these gods wage war upon each other, and they ascribed a vain glory to these false gods; none of which is worthy of the One God who is absolute in His perfection.
Fr. Tadros Yacoub Malaty
Notes
352 St. Clement of Alexandria, The Instructor 1.8.71 (FOTC 23:63).