Taken from Commentary on John II.2:
We next notice John's use of the article in these sentences. He does not write without care in this respect, nor is he unfamiliar with the niceties of the Greek tongue. In some cases he uses the article, and in some he omits it. He adds the article to the Logos, but to the name of God he adds it sometimes only. He uses the article, when the name of God refers to the uncreated cause of all things, and omits it when the Logos is named God. Does the same difference which we observe between God with the article and God without it prevail also between the Logos with it and without it? We must enquire into this. As the God who is over all is God with the article not without it, so "the Logos" is the source of that reason (Logos) which dwells in every reasonable creature; the reason which is in each creature is not, like the former called par excellence The Logos. Now there are many who are sincerely concerned about religion, and who fall here into great perplexity. They are afraid that they may be proclaiming two Gods, and their fear drives them into doctrines which are false and wicked. Either they deny that the Son has a distinct nature of His own besides that of the Father, and make Him whom they call the Son to be God all but the name, or they deny the divinity of the Son, giving Him a separate existence of His own, and making His sphere of essence fall outside that of the Father, so that they are separable from each other. To such persons we have to say that God on the one hand is Very God (Autotheos, God of Himself); and so the Saviour says in His prayer to the Father, [John 17:3] "That they may know You the only true God;" but that all beyond the Very God is made God by participation in His divinity, and is not to be called simply God (with the article), but rather God (without article). And thus the first-born of all creation, who is the first to be with God, and to attract to Himself divinity, is a being of more exalted rank than the other gods beside Him, of whom God is the God, as it is written, "The God of gods, the Lord, has spoken and called the earth." It was by the offices of the first-born that they became gods, for He drew from God in generous measure that they should be made gods, and He communicated it to them according to His own bounty. The true God, then, is "The God," and those who are formed after Him are gods, images, as it were, of Him the prototype. But the archetypal image, again, of all these images is the Word of God, who was in the beginning, and who by being with God is at all times God, not possessing that of Himself, but by His being with the Father, and not continuing to be God, if we should think of this, except by remaining always in uninterrupted contemplation of the depths of the Father.