Proofs That God the Word Is Unchangeable

We have confessed one substance of the Father, of the Son and of the Holy Spirit, and we have agreed that it is unchangeable. If, then, the Trinity has one substance, and it is unchangeable, then the only Son, who is one person of the Trinity, is unchangeable. And if he is unchangeable, he did not become flesh by being changed. He is said to have become flesh after taking flesh. [a] If God the Word became flesh by being changed into flesh, then he is not unchangeable, for no one in his right mind would call something that undergoes alteration unchangeable. And if he is changeable, he is not of one substance with the Father who begot him. For how could one part of a substance that is not made up of parts be changeable, and the other part unchangeable? If we grant this, we will fall headlong into the blasphemy of Arius and Eunomius, who say that the Son is of another substance. [b] If the Lord is of one substance with the Father, and the Son became flesh by being changed into flesh, then that substance is changeable and unchangeable at once. If anyone has the nerve to maintain this blasphemy, he will no doubt make it worse by blaspheming the Father as well. For since the Father shares the same substance, he will certainly call him changeable too. [c]

It is written in the divine Scriptures that God the Word took flesh, and a soul as well. And the most divine evangelist says that the Word became flesh. So we are forced to do one of two things. Either we must admit that the Word was changed into flesh, and reject the whole of divine Scripture, Old and New alike, as teaching lies. Or, in obedience to divine Scripture, we must confess that he took flesh, banish change from our thoughts, and receive the evangelist’s words with reverence. And this is what we must do, since we confess that the nature of God the Word is unchangeable, and we have countless testimonies that he took flesh. [d]

What lives in a tent is distinct from the tent it lives in. The evangelist calls the flesh a tent, and says that God the Word pitched his tent in it. “The Word,” he says, “became flesh and dwelt among us.” Now if he became flesh by being changed, he did not dwell in flesh. But we have been taught that he dwelt in flesh, for in another place the same evangelist calls his body a temple. So we must believe the evangelist’s own explanation and interpretation of what seemed ambiguous to some. [e] If, when the evangelist wrote, “The Word became flesh,” he had added nothing that could remove the ambiguity, then perhaps the dispute over the passage might have had some reasonable excuse in the obscurity of the words. But since he went straight on to say, “and dwelt in us,” those who fight over it fight for nothing. The first clause is explained by the second. [f]

The most wise evangelist plainly proclaims that God the Word is unchangeable. After saying, “The Word became flesh and dwelt among us,” he at once adds, “And we saw his glory, glory as of the only Son of the Father, full of grace and truth.” If, as the foolish say, he had been changed into flesh, he would not have remained what he was. But if, even when he was wrapped in the flesh, he sent out the rays of his Father’s nobility, it follows that the nature he has is unchangeable. It shines even in the body, and sends out the brightness of the nature that is unseen. For nothing can dim that light. “The light shines in the darkness, and the darkness does not comprehend it,” as the most divine John says. [g] The illustrious evangelist wanted to explain the glory of the only Son, but he could not carry out what he intended. So he shows it by his fellowship with the Father, for he says that he is of that nature. It is as though people saw Joseph sunk in a slavery unworthy of his rank, without knowing how splendid his family was, and someone pointed out to them that Jacob was his father and Abraham his forefather. In this sense the evangelist said that when he dwelt among us he did not dim the glory of his nature: “For we saw his glory, glory as of the only Son of the Father.” So if, even when he became flesh, it was plain who he was, then he remained who he was, and he did not undergo change into flesh.

We have confessed that God the Word took not only a body but a soul as well. Why, then, did the divine evangelist leave out the soul in this place and mention only the flesh? Is it not plain that he showed the visible nature, and by it pointed to the nature united with it? For the mention of the soul is, of course, understood in the mention of the flesh. When we hear the prophet say, “Let all flesh bless his holy name,” we do not take the prophet to be urging bodies of flesh without souls. We believe that in calling on a part he calls the whole to give praise. [h] The words “The Word became flesh” plainly point not to a change, but to his loving-kindness, which is beyond words. The illustrious evangelist had said, “In the beginning was the Word, and the Word was with God, and the Word was God.” He had declared him to be the Creator of things visible and invisible, and had called him life and the true light, adding other expressions like these. He had spoken about the Godhead in such terms as human reason can take in and as the language at its command can express. Then he went on, “And the Word became flesh,” as though struck with amazement and astonished at that boundless loving-kindness. He exists eternally. He is God. He made all things. He is the source of eternal life and of the true light. And for the salvation of human beings he put the tent of flesh around himself, and he was supposed to be only what he appeared to be. That is why the evangelist did not even mention a soul, but only the perishable and mortal flesh. He said nothing of the soul, since it is immortal, in order to show how boundless the kindness was. [i]

The divine apostle calls the Lord Christ the seed of Abraham. But if this is true, and true it is, then God the Word was not changed into flesh, but took on himself the seed of Abraham, as the apostle himself teaches. [j] God swore to David that from the fruit of his body, according to the flesh, he would raise up the Christ, as the prophet said and as the great Peter explained. But if God the Word was called Christ after being changed into flesh, we will find no truth anywhere in those oaths. Yet we have been taught that God cannot lie; more than that, he is himself the truth. So God the Word did not undergo change into flesh, but, in keeping with the promise, took the firstfruits of David’s seed. [k]