Nicene and Post-Nicene Fathers, Ser. II, Vol. IX:
John of Damascus: Exposition of the Orthodox Faith.: Proof that God is one and not many.

Chapter V.—Proof that God is one and not many.

We have, then, adequately demonstrated that there is a God, and that His essence is incomprehensible. But that God is one 1453 and not many is no matter of doubt to those who believe in the Holy Scriptures. For the Lord says in the beginning of the Law: I am the Lord thy God, which have brought thee out of the land of Egypt. Thou shalt have no other Gods before Me 1454 . And again He says, Hear, O Israel, the Lord our God is one Lord 1455 . And in Isaiah the prophet we read, For I am the first God and I am the last, and beside Me there is no God. Before Me there was not any God, nor after Me will there be any God, and beside Me there is no God 1456 . And the Lord, too, in the holy gospels speaketh these words to His Father, And this is life eternal, that they may know Thee the only true God 1457 . But with those that do not believe in the Holy Scriptures we will reason thus.

The Deity is perfect 1458 , and without blemish in goodness, and wisdom, and power, without beginning, without end, everlasting, uncircumscribed 1459 , and in short, perfect in all things. Should we say, then, that there are many Gods, we must recognise difference among the many. For if there is no difference among them, they are one rather than many. But if there is difference among them, what becomes of the perfectness? For that which comes short of perfection, whether it be in goodness, or power, or wisdom, or time, or place, could not be God. But it is this very identity in all respects that shews that the Deity is one and not many 1460 .

Again, if there are many Gods, how can one maintain that God is uncircumscribed? For where the one would be, the other could not be 1461 .

Further, how could the world be governed by many and saved from dissolution and destruction, while strife is seen to rage between the rulers? For difference introduces strife 1462 . And if any one should say that each rules over a part, what of that which established this order and gave to each his particular realm? For this would the rather be God. Therefore, God is one, perfect, uncircumscribed, maker of the universe, and its preserver and governor, exceeding and preceding all perfection.

Moreover, it is a natural necessity that duality should originate in unity 1463 .

Footnotes

Various reading, but that He is one.

Exod. 20:2, 3.

Deut. vi. 4.

Isa. 1:0, Isa. 43:10.

St. John xvii. 3.

See Thomas Aquin. I. quæst. 11, Art. 4; also cf. Book iv., c. 21 beneath. The question of the unity of the Deity is similarly dealt with by those of the Fathers who wrote against the Marcionites and the Manichæans, and by Athenagoras.

Or, infinite; ἀπερίγραπτον.

Infr. lib. iv. c. 21.

Greg. Nyss., Prol. Catech.

Greg. Naz., Orat. 35.

Cf. Dionys., De div. nom., c. 5, 13.