That in the Books of the Old Testament, Where It is Said that God Shall Judge the World, the Person of Christ is Not Explicitly Indicated, But It Plainly Appears from Some Passages in Which the Lord God Speaks that Christ is Meant
There are many other passages of Scripture bearing on the last judgment of God—so many, indeed, that to cite them all would swell this book to an unpardonable size. Suffice it to have proved that both Old and New Testament enounce the judgment. But in the Old it is not so definitely declared as in the New that the judgment shall be administered by Christ, that is, that Christ shall descend from heaven as the Judge; for when it is therein stated by the Lord God or His prophet that the Lord God shall come, we do not necessarily understand this of Christ. For both the Father, and the Son, and the Holy Ghost are the Lord God. We must not, however, leave this without proof. And therefore we must first show how Jesus Christ speaks in the prophetical books under the title of the Lord God, while yet there can be no doubt that it is Jesus Christ who speaks; so that in other passages where this is not at once apparent, and where nevertheless it is said that the Lord God will come to that last judgment, we may understand that Jesus Christ is meant. There is a passage in the prophet Isaiah which illustrates what I mean. For God says by the prophet, “Hear me, Jacob and Israel, whom I call. I am the first, and I am for ever: and my hand has founded the earth, and my right hand has established the heaven. I will call them, and they shall stand together, and be gathered, and hear. Who has declared to them these things? In love of you I have done your pleasure upon Babylon, that I might take away the seed of the Chaldeans. I have spoken, and I have called: I have brought him, and have made his way prosperous. Come ye near unto me, and hear this. I have not spoken in secret from the beginning; when they were made, there was I. And now the Lord God and His Spirit has sent me.” It was Himself who was speaking as the Lord God; and yet we should not have understood that it was Jesus Christ had He not added, “And now the Lord God and His Spirit has sent me.” For He said this with reference to the form of a servant, speaking of a future event as if it were past, as in the same prophet we read, “He was led as a sheep to the slaughter,” not “He shall be led;” but the past tense is used to express the future. And prophecy constantly speaks in this way.
There is also another passage in Zechariah which plainly declares that the Almighty sent the Almighty; and of what persons can this be understood but of God the Father and God the Son? For it is written, “Thus says the Lord Almighty, After the glory has He sent me unto the nations which spoiled you; for he that touches you touches the apple of His eye. Behold, I will bring mine hand upon them, and they shall be a spoil to their servants: and you shall know that the Lord Almighty has sent me.” Observe, the Lord Almighty says that the Lord Almighty sent Him. Who can presume to understand these words of any other than Christ, who is speaking to the lost sheep of the house of Israel? For He says in the Gospel, “I am not sent save to the lost sheep of the house of Israel,” which He here compared to the pupil of God's eye, to signify the profoundest love. And to this class of sheep the apostles themselves belonged. But after the glory, to wit, of His resurrection—for before it happened the evangelist said that “Jesus was not yet glorified,” — He was sent unto the nations in the persons of His apostles; and thus the saying of the psalm was fulfilled, “You will deliver me from the contradictions of the people; You will set me as the head of the nations,” so that those who had spoiled the Israelites, and whom the Israelites had served when they were subdued by them, were not themselves to be spoiled in the same fashion, but were in their own persons to become the spoil of the Israelites. For this had been promised to the apostles when the Lord said, “I will make you fishers of men.” And to one of them He says, “From henceforth you shall catch men.” They were then to become a spoil, but in a good sense, as those who are snatched from that strong one when he is bound by a stronger.
In like manner the Lord, speaking by the same prophet, says, “And it shall come to pass in that day, that I will seek to destroy all the nations that come against Jerusalem. And I will pour upon the house of David, and upon the inhabitants of Jerusalem, the spirit of grace and mercy; and they shall look upon me because they have insulted me, and they shall mourn for Him as for one very dear, and shall be in bitterness as for an only-begotten.” To whom but to God does it belong to destroy all the nations that are hostile to the holy city Jerusalem, which “come against it,” that is, are opposed to it, or, as some translate, “come upon it,” as if putting it down under them; or to pour out upon the house of David and the inhabitants of Jerusalem the spirit of grace and mercy? This belongs doubtless to God, and it is to God the prophet ascribes the words; and yet Christ shows that He is the God who does these so great and divine things, when He goes on to say, “And they shall look upon me because they have insulted me, and they shall mourn for Him as if for one very dear (or beloved), and shall be in bitterness for Him as for an only-begotten.” For in that day the Jews— those of them, at least, who shall receive the spirit of grace and mercy— when they see Him coming in His majesty, and recognize that it is He whom they, in the person of their parents, insulted when He came before in His humiliation, shall repent of insulting Him in His passion: and their parents themselves, who were the perpetrators of this huge impiety, shall see Him when they rise; but this will be only for their punishment, and not for their correction. It is not of them we are to understand the words, “And I will pour upon the house of David, and upon the inhabitants of Jerusalem, the spirit of grace and mercy, and they shall look upon me because they have insulted me;” but we are to understand the words of their descendants, who shall at that time believe through Elias. But as we say to the Jews, You killed Christ, although it was their parents who did so, so these persons shall grieve that they in some sort did what their progenitors did. Although, therefore, those that receive the spirit of mercy and grace, and believe, shall not be condemned with their impious parents, yet they shall mourn as if they themselves had done what their parents did. Their grief shall arise not so much from guilt as from pious affection. Certainly the words which the Septuagint have translated, “They shall look upon me because they insulted me,” stand in the Hebrew,“They shall look upon me whom they pierced.” And by this word the crucifixion of Christ is certainly more plainly indicated. But the Septuagint translators preferred to allude to the insult which was involved in His whole passion. For in point of fact they insulted Him both when He was arrested and when He was bound, when He was judged, when He was mocked by the robe they put on Him and the homage they did on bended knee, when He was crowned with thorns and struck with a rod on the head, when He bore His cross, and when at last He hung upon the tree. And therefore we recognize more fully the Lord's passion when we do not confine ourselves to one interpretation, but combine both, and read both “insulted” and “pierced.”
Source: City of God (New Advent)