A mystery has perplexed me for a long time—when the Word “became flesh” (John 1:14), did God change? The logic of the text seems to indicate as if this is the case: the Word was God (1:1), without flesh, and then, he “became flesh.” If one is to be strict about the lexical form of the word “became” (γίνομαι; ginomai) in John 1:14, he or she might suggest some sort of change, some sort of becoming, must have occurred. There are some other texts that might indicate there is a change in God as a result of the incarnation, e.g., Jesus is God and Jesus “grew” (Luke 2:52); Jesus “emptied himself” (Phil 2:7); and Jesus “learned” (Heb 5:8). However, we also see a plethora of texts that suggest otherwise. For example, Malachi 3:6 says, “I the Lord do not change.” Additionally, James attests that “there is no variation or shadow due to change” in the Father (Jas 1:17). If one is apt to think that the Father is unchangeable, but the Son isn’t, they are quickly hushed with Jesus’ own statement that “I and the Father are one” (John 10:30). The author of Hebrews also quiets such thoughts by confessing, “Jesus Christ is the same yesterday and today and forever” (Heb 13:8). So what are we to make of this seeming contradiction? Is God immutable (unchangeable) or did he change in the incarnation? I would answer: God is immutable and therefore he did not change in the incarnation.
Before we move on to explain how I would come to this answer, we need to offer a preliminary note. One does not merely “explain how” the incarnation happens nor how God remains immutable in the incarnation. The incarnation is like a hapax legomenon—it occurs only once. It has no analogue to which we can liken it. So, any sort of explanation is incomplete and imperfect, barely brushing up against the surface of the infinite depths of the mystery. Though we cannot fully explain how, we can confess that. And in confessing a reality, God in Scripture offers us glimpses of his glory such that we can offer incomplete descriptions of himself and his works. So, this essay is in no means an attempt to unveil the incarnation’s mystery. This is not an attempt to “solve” the mystery. Rather, it is an attempt to approach the mystery by adding a thicker lens to our glasses to see only a tad bit clearer.
1. The Foundation of Immutability: God’s Name in Exodus 3:14
Apart from the texts we noted above, the notion of divine immutability rests in God’s own name. In the burning bush revelation, Moses asks God himself for his name. God says, “I AM WHO I AM” (Exod 3:14). In verse 15, God says, “‘The LORD [יְהוָה; YHWH, Yahweh], the God of your fathers, the God of Abraham, the God of Isaac, and the God of Jacob, has sent me to you.’ This is my name…” The root of God’s name in Hebrew, means to exist (הָיָה; hayah). That God’s name signifies existence (to be) is clarified or explicated in the preceding repetition of “I am who I am.” Bound up in God’s name, nature, and existence is God’s own self-consistency. God is not who is he now and then will become something else—he simply is who he is. That is, that God is who he is implies a solid foundation that God is himself and is not and will not be otherwise. Given the tense of the verb הָיָה (hayah) “I am” (Qal Imperfect) in verse 14, the phrase could also be appropriately translated as, “I will be who I will be,” indicating that God always is himself and not some other thing, which denotes eternal duration. That God is, and that he is who he is, God not only does not change, but he cannot change, for he always is who he is. How is this still so in the incarnation?
2. The Nature of the Incarnation (Part 1): One Person
In order to understand how God is still immutable in the incarnation, we need to understand the nature (i.e., metaphysics or ontology) of the incarnation. The church has confessed that Jesus is one person, not two. Who is this person? It is none other than the second person of the Trinity, the eternal begotten, divine Son. This can be spelled out with two interrelated and mutually inclusive terms that describes the person of Christ as well as his human nature.
First, we can describe Jesus’ personhood and humanity with the term “anhypostasis” (an—non; hypostasis—person). This means that the human nature of Jesus did not possess a human person who gave it a personal identity in and of itself. There was no already existent human Jesus waiting in Mary’s womb for the divine Son to enter into him. Jesus’ humanity did not already have a human person existing, giving the human nature an identity apart from the divine Son. In short, the humanity of Jesus does not exist nor does it have its personhood in some created person apart from the eternal, divine Son.
Second, we can describe Jesus’ personhood and humanity with the term “enhypostasis” (en—in; hypostasis—person). This means that the person of the the divine Son is the person of/in his humanity. The humanity of Jesus has an identity in and from the divine Son—the eternal Son is the one who “personalizes” the humanity. Hence, the humanity of Jesus only exists in union to the divine Son.
The theological concept of an/en-hypostasis simply is a metaphysical transposition of the biblical confession that “the Word became flesh” (John 1:14), that God sent his Son, by being born from a woman (Gal 4:4), that the one who was in the form of God emptied himself by taking on the form of a servant (Phil 2:6–7), and that the μονογενὴς θεὸς (monogenēs Theos), the only begotten God, who is at the Father’s side (John 1:18) who has seen the Father and is from the Father (6:45) has made him known (1:18) and displayed his glory (1:14). This God has done to redeem mankind from the curse of sin “by sending his own Son in the likeness of sinful flesh” (Rom 8:3). And so, there is one active subject of the incarnate Son—the divine Son. This is not to deny the full humanity of Christ, rather, it is to specify what sort of humanity he assumed—a real humanity personalized by the Son. The two terms anhypostasis and enhypostasis are two sides of the same coin that confesses there is only one person of the Christ—the eternal begotten Son of God.
3. The Nature of the Incarnation (Part 2): Two Natures
Throughout Scripture we see evidences of Christ having two natures. Two lucid examples come from Paul’s prison epistles. First, we can look to Philippians 2 and the great “Christ Hymn.” Here, Paul admonishes the Philippians to have a mind like Christ Jesus “who,” he explains, “was in the form [μορφῇ; morphē] of God, did not count equality with God a thing to be grasped, but emptied himself, by taking the form [μορφὴν; morphēn] of a servant, being born in the likeness of men (ὁμοιώματι ἀνθρώπων; homoiōmati anthrōpōn)” (Phil 2:6–7). Here, we clearly see the one subject, “Christ Jesus,” has two “whats”—the form of God and the form of a servant, which is explained as being born in the likeness of men, showing Jesus has two natures: divine and human. Here, one may question the validity of both. Is Jesus really God and so have a divine nature? Paul tells us that Jesus really was “equal” (ἴσος; isos) with God and did not consider to use it for his own self-advantage (2:6). As such, since God alone is God and there is none like him (cf. Isa 46:9), to say that Jesus is equal with God is to confess that Jesus is indeed God.
Is Jesus really human if he was only born in the likeness of man? The question is valid. The term used here is “ὁμοιώματι” (homoiōmati). Paul uses this term elsewhere with reference to the incarnation in Romans 8:3: “God has done what the law, weakened by the flesh, could not do. By sending his own Son in the likeness (ὁμοιώματι; homoiōmati) of sinful flesh.” God sent his Son in the flesh, but it is a certain type of flesh. Here, we see one adjective that describes the flesh—sinful. But Paul says Jesus did not take on sinful flesh; instead, he was sent in the likeness of sinful flesh. Man was created good and without sin. As Paul already attested, Jesus is the Second or Last Adam (Rom 5:12–21; 1 Cor 15:45), representing a new humanity. “Likeness” thus suggests that Jesus was made like us in every respect, yet without sin (cf. Heb 2:14–18). Further, we must remember that sin is destruction. Sin is de-creation. Sin makes man less human. A man being without sin is being most human. And so, Jesus coming in the likeness of sinful flesh, it seems, highlights Jesus’s true and full humanity without the deteriorating stain of sin.
We also see Christ’s two natures in Colossians. Paul tells us “by him [Christ] all things were created” (Col 1:16). God and God alone creates. Paul tells us (along with other Scriptures, e.g., John 1:3 and Heb 1:2) that Jesus created everything. What does this mean? Jesus as Creator has the divine nature. Further, the one in whom all things were created is also the one in whom all things are reconciled. How is this latter reality so? Paul tells us it is so “by the blood of his [Christ’s] cross” (Col 1:20). What does this signify? Well, for one, Jesus tells us that “God is spirit” (John 4:24), and “a spirit does not have flesh and bones” (Luke 24:39). So if, God is spirit, and a spirit does not posses material “stuff” like flesh and bones, how could he have “blood” and blood is that by which Christ reconciled us according to Col 1:20? That Jesus died on the cross and shed his blood shows us that he really was a human. Paul perhaps highlights this two-nature reality of Christ in just the next chapter: “in him the whole fullness of deity dwells bodily” (Col 2:9). With this short look at only a few texts, it should be evident that Jesus, the Christ, has two natures—divine and human.
Christ has two natures, but the question we must pose now is how do these natures relate? We could think of three possible options: (1) The two natures fuse together to form one new nature—a super-divine/human nature. (2) The infinite divine nature swallows up the human nature such that the human nature dissolves into and becomes divine—just like a cup of fresh water dropped into the ocean becomes salt water. Or (3) the divine and human natures remain distinct natures while retaining and maintaining their distinctive attributes (e.g., infinite and finite, unchangeable and changeable). It is the third option that the church has adopted, which the creed of Chalcedon (AD 451) perhaps manifests most pronouncedly that Jesus is
to be acknowledged in two natures,
inconfusedly, unchangeably, indivisibly, inseparably;
the distinction of natures
being by no means taken away by the union,
but rather the property of each nature being preserved,
and concurring in one Person.
According to the church’s confession, Jesus is one person—the eternal, divine Son—who has two natures—divine and human—that are united, but are not confused, changed, divided, or separated. The distinctive properties or attributes of each nature therefore are not erased in the incarnation—the union of the divine Son to the human nature.
What this means is that if Christ’s two natures have distinct properties, we will see many things that seem to be in contradiction. For example, the one whom not even the highest heaven can contain is enclosed in the womb of a virgin; the one who upholds the universe is upheld in the manger; the one who hung the stars in place is himself hung and pierced on a tree; the one who is immortal tastes death and is buried in a grave. Divine things and human things are both said of Christ.
4. The Grammar of Christology: The Communication of Attributes
Given that Christ has two natures and is one person, we need to speak of him with a certain grammar. As we said above, Christ is one “who” (person) with two “whats” (natures). People act, not natures. So we must refrain from saying Jesus’ human nature ate, slept, hungered, etc. Therefore, the active subject of Jesus is his person and so we say Jesus ate, slept, hungered, etc. Since Jesus’ natures keep their distinct properties, everything that Jesus does, even if an act befits one nature and not the other, is predicated to (i.e., asserted to or spoken of) his one person—the divine Son. Christ’s person acts, not his natures. His natures are that by which he acts. So some acts are befitting to his divinity and others are befitting to his humanity, yet all of these acts are achieved by Christ’s one person—the divine Son—and so all acts are said to be the divine Son’s acts. This grammar thus allows us to speak of human things (eating, growing, dying) about the divine person, and conversely, speak of divine things to the human Jesus (e.g., he has the authority to forgive sins).
5. The Incarnation and the Immutability of God
All of the preceding material lays the foundation for speaking of God staying the same even as the Son became flesh. We can lay this out in numeral format:
1. Jesus is one person—the divine Son.
2. Jesus has two natures—divine and human.
3. Jesus’ two natures maintain their distinct properties.
4. When Jesus acts in ways that befit properties of a certain nature, they are still spoken of his one person because persons act, not natures.
We can apply this grammar to the incarnation. If “becoming” (i.e., change) is proper to humans—they come into existence, they grow, etc.—we can speak of the Word’s “becoming” as being proper to his human nature. Since Christ’s human nature is his own human nature such that it comes into existence only in union with the Word, we speak of the “becoming” as of the divine Word. So, while coming into existence is fitting and proper to human creatures and their natures, that act is predicated to Christ’s divine person—the eternal Word, the only begotten Son of God.
Now, some might push back and rightly state the emphasis of the Word becoming flesh is not on the passivity of the flesh receiving an identity from the eternal Word, but rather, the emphasis is on the subject of the sentence: “the Word became flesh”—the Word exists in a way it did not before. Though this is right, the grammar and proposal still stands. Though the Word exists in a “new” way, what is new is not the Word, but rather the union (or relation) to the humanity, and so, the humanity’s existence is new. In other words, there are two aspects to the incarnation, which can be implied the a central gospel statement of Jesus: “I have come down from heaven, not to do my own will but the will of him who sent me” (John 6:38). Being sent implies two things: (1) there is a source or origin of the sending of the Son, and (2) there is a temporal effect. The origin (God) does not change, but the temporal effect (the new manner in which the person exists) is indeed “new,” and the temporal effect is the humanity of Christ.
Nevertheless, we must remember that the newness of the humanity is still said of the divine Son because it is he who gives the humanity existence, it is he who is the person of Jesus’ humanity. The humanity does not exist in and of itself, but it exists only in the divine Son, that is, its existence is only in the existence of the divine Son. The humanity is the humanity of the Word—it is not a passive thing already existing and waiting a personal identity. As such, when the Word becomes flesh, the locus of the becoming is in the existence of the humanity, which alone has existence in the Son’s union to it.
6. The Word “Became”? The Meaning(s) of Ginomai in John 1:1–15
There is a lexical (or terminological) rationale for this. The term John uses to describe the Word’s becoming flesh is “ἐγένετο” (egeneto), which comes from the word “γίνομαι” (ginomai). John uses this term repeatedly before 1:14 to indicate coming into existence of a number of things—the “birth” or “becoming” of creation (1:3 [3x], 10), and those who “become” children of God (1:12). John explains what becoming (γενέσθαι [genesthai; v. 12]) children of God by pairing it with “born” language in verse 13: “who were born [ἐγεννήθησαν; egennethēsan], not of blood nor of the will of the flesh nor of the will of man, but of God.” Hence, before 1:14, ginomai seems to mean the “coming into existence as such” for John.
In verse 15, we see an interesting use of ginomai. John the Baptist exclaims, “This was he of whom I said, ‘He who comes after me ranks before me, because he was [γέγονεν; gegonen—from ginomai] before me.’” However, John the Baptist is not using ginomai here in the sense of speaking about Jesus’ birth—his coming into existence as Mary’s son. We know this because he says “he was before me.” “Was” does not mean “born” here since, as Luke’s gospel tells us, Jesus was born after John the Baptist was born (cf. Luke 1–2). That the Word “was” before John the Baptist recalls to mind the gospel’s commencement in John 1:1–2: “In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God.” The Word was (existed) before John the Baptist.
How does this contribute to our understanding of God’s immutability in the incarnation? Given the use of ginomaibefore 1:14 as indicating things coming into existence and given the use of ginomai with reference to the Word after 1:14 indicates that the Word pre-existed John the Baptist, we see that ginomai can be used in various senses as is clear from a number of other texts (e.g., in the immediate context, 1:6). Preceding the confession that the Word became flesh, ginomai is used to highlight coming into existence (either in toto [totality] or in a new way—from children of Adam to children of God, which still indicates some sort of “new creation” [cf. 2 Cor 5:21]). Succeeding the confession that the Word became flesh, ginomai is used to show and recall that the Word has always existed—that he never came into being. What seems to be at play here is careful wording by the Fourth Evangelist. There is a sense in which the Word “became” without becoming. The Word is always the Word—he is never “new” nor has he ever come into existence; he is eternal. But, the way in which he is new is located in his flesh and his flesh’s coming into existence, which is only in the very person of the Son (an/en-hypostasis). In this way, the Word “became” or came into existence according to his flesh that came into existence, while the Word itself did not become in and of itself anything new according to nature, for the Word has always existed as the Word. In other words, the Word exists in a new way, the Word per se does not exist newly—what is new is the Word’s flesh that has its existence only in the Word.
We must note that this proposal is only a way one could possibly argue for God to remain immutable in the incarnation. One could certainly argue that we should read John 1:14 with Philippians 2:7: he who was in the form of God took (λαβών; labōn) on the form of a servant. Further, one may suggest that since Jesus remained God, which is clear throughout the rest of the Gospel of John (e.g., 8:58; 14:9; 17:5; 19:37; 20:28; 20:31), God must have been the same otherwise he would not be God, for if God changed, he would be other than who he is. Additionally, one could make an argument from the standpoint of God’s relation to time. All this is to say that the grammar founded upon the ontology of the incarnation may aid us in confessing that the Word became flesh while affirming God does not change.
7. Conclusion: Why Does It Matter That God Is Immutable?
We might conclude this essay with a brief, yet important question: Why does this matter? Why is it significant for the Christian life that God remains unchangeable in the incarnation—or in anything? We might note a few reasons.
First, to confess that God is unchangeable is to honor God as incorruptible. Twice Paul calls God “immortal” or “incorruptible” (ἄφθαρτος; aphthartos) where God’s glory is concerned—whether in idolatry (Rom 1:23) or in appropriate praise (1 Tim 3:17). If we are to confess that God in his glory is incorruptible, unfading, unable to be diminished, we not only speak of his unending and incomprehensible glory, but we also indicate something about our own joy. If indeed God is most glorified in us when we are most satisfied in him, that is, if our joy really rests in God’s own glory, when we affirm God’s immutable and incorruptible glory, we also attest that in him we “rejoice with joy that is inexpressible and filled with glory” (1 Pet 1:8).
Second, if God is immutable, our confidence is sure in a fickle world. As this unchangeable one, Scripture calls God our Rock (1 Sam 2:2). This is great comfort not only in the inconsistent waves of the economy or the cares of this world that act as tides, pulling our worries in one direction and then the next, but it also consoles the sorrowful soul that questions their own salvation. “Because of the inconstancy of their own heart, together with the immutable treacheries of their spiritual enemies, what will sustain the more effectively than the fact that their immutable God (Mal. 3:6) is a rock and in moved boulder, whose firm foundation stands, by which the Lord knows those who are his (2 Tim. 2:19)…?” When we know and love God in his immutability, we can trust he will “support us in our unsteadiness.”
Finally, if we really bear God’s image and are to conform to the image of Christ (Rom 8:29), who is the image of the invisible God (Col 1:15) who is immutable, divine immutability not only has a metaphysical/ontological shape but also a moral dimension. Scripture chastises a man with double or fickle mind and calls him to draw near to God (Jas 1:8; 4:8). Reflecting divine immutability gives us ground to remain faithful not only to our spouses, but also to hold fast the confession of our faith.
The mystery of the incarnation is infinitely deep because its origin is in one whose understanding is unsearchable (Isa 40:28). And this one, our Holy One, is an unshakeable, unchanging Rock—and there is not rock like our God (1 Sam 2:2).
 Herman Bavinck puts it this way: “If God were not immutable, he would not be God. [God’s] name is ‘being,’ and this name is ‘an unalterable name.’ All that changes ceases to be what it was. But true being belongs to him who does not change. That which truly is remains” (Herman Bavinck, Reformed Dogmatics, 2:154.
 See Thomas Aquinas, Summa theologiae Ia.43.2 ad. 2–3.
 See Petrus van Mastricht, Theoretical-Practical Theology, I.ii.7 [p. 161].
 Mastricht, Theoretical-Practical Theology, I.ii.7 [p. 162].
 Mastricht, Theoretical-Practical Theology, I.ii.7 [p. 163].