He then exposes the ignorance of Eunomius, and the incoherence and absurdity of his arguments, in speaking of the Son as the Angel of the Existent, and as being as much below the Divine Nature as the Son is superior to the things created by Himself. And in this connection there is a noble and forcible counter-statement and an indignant refutation, showing that He Who gave the oracles to Mosesis Himself the Existent, the Only-begotten Son, Who to the petition of Moses, If You Yourself go not with us, carry me not up hence, said, I will do this also that you have said ; Who is also called Angel both by Moses and Isaiah: wherein is cited the text, Unto us a Child is born
But he strives to prop up his absurdity by the testimony of Scripture, and puts forth Moses as his advocate against the truth. For as though that were the source from which he drew his arguments, he freely sets forth to us his own fables, saying, “He Who sent Moses was the Existent Himself, but He by Whom He sent and spoke was the Angel of the Existent, and the God of all else.” That his statement, however, is not drawn from Scripture, may be conclusively proved by Scripture itself. But if he says that this is the sense of what is written, we must examine the original language of Scripture. Moreover let us first notice that Eunomius, after calling the Lord God of all things after Him, allows Him no superiority in comparison with the angelic nature. For neither did Moses, when he heard that he was made a god to Pharaoh, pass beyond the bounds of humanity, but while in nature he was on an equality with his fellows, he was raised above them by superiority of authority, and his being called a god did not hinder him from being man. So too in this case Eunomius, while making out the Son to be one of the angels, salves over such an error by the appellation of Godhead, in the manner expressed, allowing Him the title of God in some equivocal sense. Let us once more set down and examine the very words in which he delivers his blasphemy. “He Who sent Moses was the Existent Himself, but He by Whom He sent was the Angel of the Existent”— this, namely “Angel,” being the title he gives his Lord. Well, the absurdity of our author is refuted by the Scripture itself, in the passage where Moses beseeches the Lord not to entrust an angel with the leadership of the people, but Himself to conduct their march. The passage runs thus: God is speaking, “Go, get you down, guide this people unto the place of which I have spoken unto you: behold Mine Angel shall go before you in the day when I visit.” And a little while after He says again, “And I will send Mine Angel before you.” Then, a little after what immediately follows, comes the supplication to God on the part of His servant, running on this wise, “If I have found grace in Your sight, let my Lord go among us,” and again, “If You Yourself go not with us, carry me not up hence”; and then the answer of God to Moses, “I will do for you this thing also that you have spoken: for you have found grace in My sight, and I know you above all men.” Accordingly, if Moses begs that the people may not be led by an angel, and if He Who was discoursing with him consents to become his fellow-traveller and the guide of the army, it is hereby manifestly shown that He Who made Himself known by the title of “the Existent” is the Only-begotten God.
If any one gainsays this, he will show himself to be a supporter of the Jewish persuasion in not associating the Son with the deliverance of the people. For if, on the one hand, it was not an angel that went forth with the people, and if, on the other, as Eunomius would have it, He Who was manifested by the name of the Existent is not the Only-begotten, this amounts to nothing less than transferring the doctrines of the synagogue to the Church of God. Accordingly, of the two alternatives they must needs admit one, namely, either that the Only-begotten God on no occasion appeared to Moses, or that the Son is Himself the “Existent,” from Whom the word came to His servant. But he contradicts what has been said above, alleging the Scripture itself which informs us that the voice of an angel was interposed, and that it was thus that the discourse of the Existent was conveyed. This, however, is no contradiction, but a confirmation of our view. For we too say plainly, that the prophet, wishing to make manifest to men the mystery concerning Christ, called the Self-Existent “Angel,” that the meaning of the words might not be referred to the Father, as it would have been if the title of “Existent” alone had been found throughout the discourse. But just as our word is the revealer and messenger (or “angel”) of the movements of the mind, even so we affirm that the true Word that was in the beginning, when He announces the will of His own Father, is styled “Angel” (or “Messenger”), a title given to Him on account of the operation of conveying the message. And as the sublime John, having previously called Him “Word,” so introduces the further truth that the Word was God, that our thoughts might not at once turn to the Father, as they would have done if the title of God had been put first, so too does the mighty Moses, after first calling Him “Angel,” teach us in the words that follow that He is none other than the Self-Existent Himself, that the mystery concerning the Christ might be foreshown, by the Scripture assuring us by the name “Angel,” that the Word is the interpreter of the Father's will, and, by the title of the “Self-Existent,” of the closeness of relation subsisting between the Son and the Father. And if he should bring forward Isaiah also as calling Him “the Angel of mighty counsel,” not even so will he overthrow our argument. For there, in clear and uncontrovertible terms, there is indicated by the prophecy the dispensation of His Humanity; for “unto us,” he says, “a Child is born, unto us a Son is given, and the government shall be upon His shoulder, and His name is called the Angel of mighty counsel.” And it is with an eye to this, I suppose, that David describes the establishment of His kingdom, not as though He were not a King, but in the view that the humiliation to the estate of a servant to which the Lord submitted by way of dispensation, was taken up and absorbed into the majesty of His Kingdom. For he says, “I was established King by Him on His holy hill of Sion, declaring the ordinance of the Lord.” Accordingly, He Who through Himself reveals the goodness of the Father is called “Angel” and “Word,” “Seal” and “Image,” and all similar titles with the same intention. For as the “Angel” (or “Messenger”) gives information from some one, even so the Word reveals the thought within, the Seal shows by Its own stamp the original mould, and the Image by Itself interprets the beauty of that whereof It is the image, so that in their signification all these terms are equivalent to one another. For this reason the title “Angel” is placed before that of the “Self-Existent,” the Son being termed “Angel” as the exponent of His Father's will, and the “Existent” as having no name that could possibly give a knowledge of His essence, but transcending all the power of names to express. Wherefore also His name is testified by the writing of the Apostle to be “above every name,” not as though it were some one name preferred above all others, though still comparable with them, but rather in the sense that He Who verily is is above every name.
Source: Against Eunomius (New Advent)