23 What further fictions can the futile folly of insane blasphemy devise? Do you still persist in your nightly sowing of tares, predestined to be burnt, among the pure wheat, when the knowledge of all the Patriarchs contradicts you? Nay more: if you believed Moses, you would believe also in God, the Son of God; unless perchance you deny that it was of Him that Moses spoke. If you propose to deny that, you must listen to the words of God:— For had ye believed Moses, you would have believed Me also, for he wrote of Me. Moses, indeed, will refute you with the whole volume of the Law, ordained through angels, which he received by the hand of the Mediator.
Enquire whether He, Who gave the Law, were not true God; for the Mediator was the Giver. And was it not to meet God that Moses led out the people to the Mount? Was it not God Who came down into the Mount? Or was it, perhaps, only by a fiction or an adoption, and not by right of nature, that He, Who did all this, bore the name of God? Mark the blare of the trumpets, the flashing of the torches, the clouds of smoke, as from a furnace, rolling over the mountain, the terror of conscious impotence on the part of man in the presence of God, the confession of the people, when they prayed Moses to be their spokesman, that at the voice of God they would die.
Is He, in your judgment, not true God, when simple dread lest He should speak filled Israel with the fear of death? He Whose voice could not be borne by human weakness? In your eyes is He not God, because He addressed you through the weak faculties of a man, that you might hear, and live? Moses entered the Mount; in forty days and nights he gained the knowledge of the mysteries of heaven, and set it all in order according to the vision of the truth which was revealed to him there.
From intercourse with God, Who spoke with him, he received the reflected splendour of that glory on which none may gaze? His corruptible countenance was transfigured into the likeness of the unapproachable light of Him, with Whom he was dwelling. Of this God he bears witness, of this God he speaks; he summons the angels of God to come and worship Him amid the gladness of the Gentiles, and prays that the blessings which please Him may descend upon the head of Joseph. In face of such evidence as this, dare any man say that He has nothing but the name of God, and deny His true Divinity?
Source: On the Trinity (New Advent)