Celsus proceeds to say of God that “of Him are all things,” abandoning (in so speaking), I know not how, all his principles; while our Paul declares, that “of Him, and through Him, and to Him are all things,” showing that He is the beginning of the substance of all things by the words “of Him,” and the bond of their subsistence by the expression “through Him,” and their final end by the terms “to Him.” Of a truth, God is of nothing. But when Celsus adds, that “He is not to be reached by word,” I make a distinction, and say that if he means the word that is in us— whether the word conceived in the mind, or the word that is uttered — I, too, admit that God is not to be reached by word.
If, however, we attend to the passage, “In the beginning was the Word, and the Word was with God, and the Word was God,” we are of opinion that God is to be reached by this Word, and is comprehended not by Him only, but by any one whatever to whom He may reveal the Father; and thus we shall prove the falsity of the assertion of Celsus, when he says, “Neither is God to be reached by word.” The statement, moreover, that “He cannot be expressed by name,” requires to be taken with a distinction.
If he means, indeed, that there is no word or sign that can represent the attributes of God, the statement is true, since there are many qualities which cannot be indicated by words. Who, for example, could describe in words the difference between the quality of sweetness in a palm and that in a fig? And who could distinguish and set forth in words the peculiar qualities of each individual thing? It is no wonder, then, if in this way God cannot be described by name. But if you take the phrase to mean that it is possible to represent by words something of God's attributes, in order to lead the hearer by the hand, as it were, and so enable him to comprehend something of God, so far as attainable by human nature, then there is no absurdity in saying that “He can be described by name.”
And we make a similar distinction with regard to the expression, “for He has undergone no suffering that can be conveyed by words.” It is true that the Deity is beyond all suffering. And so much on this point.
Source: Against Celsus (New Advent)