Apology of Aristides (Early 2nd Century) Chapter 1:
I say, then, that God is not born, not made, an ever-abiding nature without beginning and without end, immortal, perfect, and incomprehensible. Now when I say that he is "perfect," this means that there is not in him any defect, and he is not in need of anything but all things are in need of him. And when I say that he is "without beginning," this means that everything which has beginning has also an end, and that which has an end may be brought to an end. He has no name, for everything which has a name is kindred to things created. Form he has none, nor yet any union of members; for whatsoever possesses these is kindred to things fashioned. He is neither male nor female. The heavens do not limit him, but the heavens and all things, visible and invisible, receive their bounds from him. Adversary he has none, for there exists not any stronger than he. Wrath and indignation he possesses not, for there is nothing which is able to stand against him. Ignorance and forgetfulness are not in his nature, for he is altogether wisdom and understanding; and in Him stands fast all that exists. He requires not sacrifice and libation, nor even one of things visible; He requires not aught from any, but all living creatures stand in need of him.
Justin Martyr’s Hortatory Address to the Greeks (Mid-2nd Century) Chapter 21:
For God cannot be called by any proper name, for names are given to mark out and distinguish their subject-matters, because these are many and diverse; but neither did any one exist before God who could give Him a name, nor did He Himself think it fight to name Himself, seeing that He is one and unique, as He Himself also by His own prophets testifies, when He says, "I God am the first," and after this, "And beside me there is no other God." On this account, then, as I before said, God did not, when He sent Moses to the Hebrews, mention any name, but by a participle He mystically teaches them that He is the one and only God. "For," says He; "I am the Being;" manifestly contrasting Himself, "the Being," with those who are not, that those who had hitherto been deceived might see that they were attaching themselves, not to beings, but to those who had no being. Since, therefore, God knew that the first men remembered the old delusion of their forefathers, whereby the misanthropic demon contrived to deceive them when he said to them, "If ye obey me in transgressing the commandment of God, ye shall be as gods," calling those gods which had no being, in order that men, supposing that there were other gods in existence, might believe that they themselves could become gods. On this account He said to Moses, "I am the Being," that by the participle "being" He might teach the difference between God who is and those who are not. Men, therefore, having been duped by the deceiving demon, and having dared to disobey God, were cast out of Paradise, remembering the name of gods, but no longer being taught by God that there are no other gods. For it was not just that they who did not keep the first commandment, which it was easy to keep, should any longer be taught, but should rather be driven to just punishment. Being therefore banished from Paradise, and thinking that they were expelled on account of their disobedience only, not knowing that it was also because they had believed in the existence of gods which did not exist, they gave the name of gods even to the men who were afterwards born of themselves. This first false fancy, therefore, concerning gods, had its origin with the father of lies. God, therefore, knowing that the false opinion about the plurality of gods was burdening the soul of man like some disease, and wishing to remove and eradicate it, appeared first to Moses, and said to him, "I am He who is." For it was necessary, I think, that he who was to be the ruler and leader of the Hebrew people should first of all know the living God. Wherefore, having appeared to him first, as it was possible for God to appear to a man, He said to him, "I am He who is;" then, being about to send him to the Hebrews, He further orders him to say, "He who is hath sent me to you."
Justin Martyr’s Dialog with Trypho (Mid-2nd Century) Chapter 127:
wherever God says, 'God went up from Abraham,' or, 'The Lord spake to Moses,' and 'The Lord came down to behold the tower which the sons of men had built,' or when 'God shut Noah into the ark,' you must not imagine that the unbegotten God Himself came down or went up from any place. For the ineffable Father and Lord of all neither has come to any place, nor walks, nor sleeps, nor rises up, but remains in His own place, wherever that is, quick to behold and quick to hear, having neither eyes nor ears, but being of indescribable might; and He sees all things, and knows all things, and none of us escapes His observation; and He is not moved or confined to a spot in the whole world, for He existed before the world was made. How, then, could He talk with any one, or be seen by any one, or appear on the smallest portion of the earth, when the people at Sinai were not able to look even on the glory of Him who was sent from Him; and Moses himself could not enter into the tabernacle which he had erected, when it was filled with the glory of God; and the priest could not endure to stand before the temple when Solomon conveyed the ark into the house in Jerusalem which he had built for it? Therefore neither Abraham, nor Isaac, nor Jacob, nor any other man, saw the Father and ineffable Lord of all, and also of Christ, but [saw] Him who was according to His will His Son
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Find more of what the early Christians thought on my Christian History page!