“Cur Deus Homo?” – or “Why did God become Man?” – is perhaps one of the most important questions posed in the history of the Church. It is a question that is not only critical to correctly understanding the doctrine of God, as well as the doctrine of Christ, but it is also critical to our understanding of the Gospel itself. In fact, it can be argued that most of the debates between the Patristic Fathers were, at the very least, indirectly related to this question. However, the direct question of “Why did God become Man” would come at end of the 11th Century when Anselm of Canterbury would write a book entitled with this very question, thus laying the groundwork for the further clarification of Christology in the Western Church. Indeed, over five centuries later, and fifty miles to the northwest of Canterbury, the Westminster Assembly would pick up Anselm’s mantle and carry it forward as they sought to reform the Church that Anselm called home.
As we conclude our introduction to Westminster Christology – having previously examined our need for a mediator as well as the eternal generation of the Son – we are going to consider two questions in the vein of Anselm; “how the God-man?” and “why the God-man?”
“How” the God-man?
The end of Larger Catechism 36 answers this question by saying:
Q36: Who is the Mediator of the covenant of grace?
A36: The only Mediator of the covenant of grace is the Lord Jesus Christ, who, being the eternal Son of God, of one substance and equal with the Father, in the fulness of time became man, and so was and continues to be God and man, in two entire distinct natures, and one person, forever.
As we recounted in our previous installment on Christology, the person of the Son of God is eternally generated out of the subsistence – or the “person” – of the Father, thus making it fitting for Him to likewise be temporarily generated in a human nature when the “fulness of time” came. Orthodox Christians have always recognized that Jesus was both God and man from his conception in the womb of the Virgin Mary; yet “how” this is so, was a question that the early church continually wrestled with. Was Jesus “partly” God, and “partly man?” Did the natures blend together, making Jesus a sort of composite being? Or was Jesus simply a human person who was in the most perfect of unions with the divine Son of God/Logos?
If you are new to Christology – or are unfamiliar with the debates of the Church fathers – the answer to all of those questions is decidedly no. And, yet, to those who haven’t studied the doctrine of Christ, these might sound like reasonable ways of framing the question. It is at this point that the value is found in catechism, as the mature reflections of the Church are simplified and clarified, often into a few simple sentences. According to the Westminster Divines, how are we to conceive of Jesus being both God and man?
The orthodox answer to “‘How’ the God-man,” is found in the Larger Catechism 36 where it states that Jesus is God and man “in two entire distinct natures, and one person.” In other words, Christ is not “partly God” or “partly man,” but entirely God and entirely man. On the other hand, the natures are not blended together, as they remain distinct (yet not separate), being in union with the one person. Likewise, since the natures are united to the “one person,” this precludes any conception of there being a human person on earth named Jesus, and a divine person in heaven called the Son of God/Logos. On the contrary, the orthodox understanding is that Jesus is one person, with two natures (after His incarnation, that is). This is what theologians often call the doctrine of the “hypostatic union.” A further exposition of this doctrine is found in the Westminster Confession chapter 8, on Christ the Mediator.
“…the Godhead and the manhood, were inseparably joined together in one person, without conversion, composition, or confusion. Which person is very God and very man, yet one Christ, the only mediator between God and man.” WCF 8.2
Being rooted in Patristic theology, the Westminster Divines mirror the exact language of the Formula of Chalcedon (451AD), where they describe this union as being “without conversion, composition, or confusion.” In other words, due to the union of the natures in the person of the Son, the natures remain intact, as they are distinct but not separate.
While this is a great mystery which transcends our understanding, it fully accounts for the empirical data provided for us by divine revelation. When Jesus was conceived, when He was born, when He grew – He really experienced these things in His human nature just as you do. When He wept, showed compassion, was abused, and expressed sorrow – He really experienced those things as you do, yet without sin. Likewise, when He performed miracles, claimed the divine name, and forgave men of their sins – He did so being coextensive with the Godhead and the other persons of the Trinity. You see, our creedal and confessional heritage not only crystallizes our understanding of how Christ is both God and man, but it also allows us to, contra the claims of popular evangelicalism, take what the Scriptures say about Him at face value.
But why does knowing this really matter? Robert Letham in his book, “The Holy Trinity”, observes that to many evangelical Christians, the doctrine of the Trinity is simply a mathematical conundrum with little to no practical value. In a similar fashion, an esoteric doctrine like the hypostatic union can easily be seen in a similar light; a theological puzzle to be mused upon by seminary students and armchair theologians. So in what way does this doctrine matter to the average Christian’s faith and piety?
Why the God-man?
The key to understanding why Christ had to be both God and man is His role as Mediator, as the beginning of Larger Catechism 36 brings to our attention. Our Lord had to be both God and man in order that He might reconcile God to man. This reconciliation can be seen in seminal form in the very union of His divine and human natures itself, as in His person He represents the joining together of the creature with the Creator. In other words, in the most intimate way possible, the Son of God mediates between God and man out of this hypostatic union. As I mentioned in our first installment in this series, when we gaze into the human face of Jesus Christ, we can also accurately say that we are gazing upon the face of God! In this way Christ mediates the presence and knowledge of God to finite and feeble creatures such as us.
In the Christian East this aspect of Christ as Mediator is understood to be the “main event,” which is why the Eastern Orthodox tends to focus on the Incarnation and Resurrection while downplaying the atonement. However, in the West, it has always been emphasized that not only does Christ mediate for us through the union of His natures, but also through the distinct works of each nature. This is reflected in what the divines state in Larger Catechism 38 and 39:
Q38: Why was it requisite that the Mediator should be God?
A38: It was requisite that the Mediator should be God, that he might sustain and keep the human nature from sinking under the infinite wrath of God, and the power of death; give worth and efficacy to his sufferings, obedience, and intercession; and to satisfy God’s justice, procure his favor, purchase a peculiar people, give his Spirit to them, conquer all their enemies, and bring them to everlasting salvation.
Q39: Why was it requisite that the Mediator should be man?
A39: It was requisite that the Mediator should be man, that he might advance our nature, perform obedience to the law, suffer and make intercession for us in our nature, have a fellow feeling of our infirmities; that we might receive the adoption of sons, and have comfort and access with boldness unto the throne of grace.
These two questions and answers really get to the heart of the matter of “Cur Deus Homo?” Our mediator had to be God in order that He might uphold His human nature, give it infinite worth in His sufferings and obedience, and exercise the divine prerogatives in saving His people (i.e. give His Spirit to them, conquer their enemies, and bring them to everlasting salvation etc..). In Jesus Christ, we see the faithful covenant Lord come down to “meet us where we are at” and powerfully deliver us from our bondage.
However, LC 39 goes on to truly reflect the legacy of Anselm and other Western theologians in emphasizing the necessity of Christ’s human obedience and sacrifice. As Anselm summarily taught in his theology, the same nature that dishonored God through sin, must also make restitution by honoring God through obedience and sacrifice. In the reformation era, this understanding was formulated around the concept of satisfaction. The Heidelberg Catechism in Q/A 16 says that Jesus had to be a true and righteous man because “the same human nature which has sinned should make satisfaction for sin.” In other words, Jesus had to perform our duty for us in satisfying God by active obedience as well as passive obedience (i.e. submitting to the punishment due to us).
This simply distills and propounds for us the theology of Paul, where He speaks of Christ “taking the form of a bondservant, and coming in the likeness of men” (Phil. 2:7b NKJV); or when he teaches the Galatians that “when the fullness of the time had come, God sent forth His Son, born of a woman, born under the law, to redeem those who were under the law, that we might receive the adoption as sons” (Gal 4:4,5 NKJV). Jesus is not only the covenant Lord come in the flesh, but He is also the faithful covenant servant, performing our duty for us.
This truly gets to the heart of “Why the God-man?” Evangelicals often speak of the Christian faith as being about a “personal relationship with Jesus Christ.” While this is often reflective of warmed over emotionalism and sentimentalism, it isn’t far from what the Gospel actually teaches when correctly understood. Indeed, we have the most personal and intimate of relationships with the God of the universe because of the fact that Jesus Christ is our mediator!
Jesus is the God who created us, upholds us, and is the very ground of reality. He is the God to whom the Psalmist says, “Where can I go from Your Spirit? Or where can I flee from Your presence?” (Psalm 139:7 NKJV). But He is also the very person of God made flesh, or God made one of us. When we look to Him with the eye of faith, we are not only looking into the face of our God, the faithful covenant Lord come to save us, but we are also beholding the face of our brother and friend who has come to serve and satisfy the divine justice when we could not. Truly, answering “Cur Deus Homo,” is a precious truth that is key to rightly believing and resting in the glorious Gospel of the God-man.
Q40: Why was it requisite that the Mediator should be God and man in one person ?
A40: It was requisite that the Mediator, who was to reconcile God and man, should himself be both God and man, and this in one person, that the proper works of each nature might be accepted of God for us, and relied on by us, as the works of the whole person.