Why celebrate the birth of Christ?
This year’s Christmas advert from Marks and Spencer asks the question what is the ‘must have’ which ‘makes Christmas, Christmas’? The advert’s answers to this question include lights, parties and various types of women’s underwear, but from a Christian perspective all these answers miss the one ‘must have’ which genuinely ‘makes Christmas, Christmas,’ which is the birth of Jesus Christ.
For Christians the whole point of Christmas is to celebrate Jesus being born as a human being in Bethlehem from the Virgin Mary. From a Christian point of view to celebrate Christmas without celebrating Jesus’ birth, is to have an event that is missing its essential element. It is like having a feast with no food to eat, a coronation with no one to crown, or an election with no one to elect.
When Christians say that the point of Christmas is to celebrate the birth of Jesus Christ this leads, of course, to the response ‘Why is this birth worth celebrating’? In this post I shall address this response by looking at why the birth of Jesus Christ is the one ‘must have’ for all human beings and for that reason something which should be celebrated.
C S Lewis on why the birth of Christ matters.
A helpful way to begin to understand the necessity of the birth of Jesus Christ is provided by C S Lewis in his book Mere Christianity. He starts by noting that there are two different kinds of life. The first is what he calls the natural life. This is the created life that all human beings possess as a result of having been called into existence out of nothing by God. The second is what he calls the begotten life. This is the eternal spiritual life which God the Son possesses as a result of having come forth from God the Father.
God’s will for his human creatures, he says, is that they should possess both kinds of life and so live for ever as God’s children. However, in the world as it exists today these two kinds of life are:
‘…not only different (they would always have been that) but actually opposed. The natural life in each of us is something self-centred, something that wants to be petted and admired, to take advantage of other lives, to exploit the whole universe. And especially it wants to be left by itself: to keep well away from anything better or stronger or higher than it, anything that might make it feel small. It is afraid of the light and air of the spiritual world, just as those who have been brought up to be dirty are afraid of a bath. And in a sense it is quite right. It knows that if the spiritual life gets hold of it, all its self-centredness and self-will are going to be killed and it is ready to fight tooth and nail to avoid that.’ 
As an analogy, Lewis asks us to imagine what would be involved in an old fashioned tin soldier becoming a real human being:
‘It would involve turning the tin into flesh. And suppose the tin soldier did not like it. He is not interested in flesh; all he sees is that the tin is being spoilt. He thinks you are killing him. He will do everything he can to prevent you. He will not be made into a man if he can help it.’ 
Having explained that this is the human situation, Lewis then goes on to explain how God has dealt with it through the birth of Jesus Christ. He writes:
‘What you would have done about that tin soldier I do not know. But what God did about us was this. The Second Person in God, the Son, became human Himself: was born into the world as an actual man – a real man of a particular height, with hair of a particular colour, speaking a particular language, weighing so many stone. The Eternal Being, who knows everything and who created the whole universe, became not only a man but (before that) a baby, and before that a foetus inside a Woman’s body.’
The result of God’s action was that:
‘…you now had one man who really was what all men were intended to be: one man in whom the created life, derived from his Mother, allowed itself to be completely and perfectly turned into the begotten life. The natural human creature in Him was taken up fully into the divine Son. Thus in one instance humanity had, so to speak, arrived: had passed into the life of Christ. And because the whole difficulty for us is that the natural life has to be, in a sense, ‘killed,’ he chose an earthly career which involved the killing of His human desires at every turn – poverty, misunderstanding from his own family, betrayal from one of His intimate friends, being jeered at and manhandled by the Police, and execution by torture. And then, after being thus killed – killed every day in a sense – the human creature in Him, because it was united to the divine Son, came to life again. The Man in Christ rose again: not only the God. That is the whole point. For the first time we saw a real man. One tin soldier – real tin, just like the rest – had come fully and splendidly alive.’ 
The significance of all this for us, declares Lewis, is that what Christ did by his living, and dying and rising has affected humanity as a whole and has open door of salvation for every member of the human race. In his words:
‘What, then, is the difference which he has made to the whole human mass? It is just this: that the business of becoming a son of God, of being turned from a created thing to a begotten thing, of passing over from the temporary biological life into timeless ‘spiritual’ life, has been done for us. Humanity is already ‘saved’ in principle. We individuals have to appropriate that salvation. But the really tough work – the bit we could not have done for ourselves – has been done for us. We have not got to try to climb up into spiritual life by our own efforts: it has already come down into the human race. If we will only lay ourselves open to the one Man in whom it was fully present, and who, in spite of being God, is also a real man, He will do it in us and for us. Remember what I said about ‘good infection.’ One of our own race has this new life: if we get close to Him we shall catch it from Him.’
How the Bible confirms what is said by Lewis
In this section of Mere Christianity Lewis does not quote any specific passages from Scripture. However, what he writes can be viewed as an explanation of the teaching of the Bible as a whole about what Christ came to do.
The Bible teaches us that ‘sin came into the world through one man and death through sin, and so death spread to all men because all men sinned’ (Romans 5:12). In specific terms we are told that Adam, the first human being, rebelled against God by eating of the fruit of the tree of the knowledge of good and evil and that he and his wife Eve, who was complicit in his sin, were expelled from the Garden of Eden and being thus cut off from the tree of life became subject to death (Genesis 3:1-24). The point that is being made by this story is that sin leads to death. Why? Because, as Lewis argues, sin involves turning away from God and the spiritual life that he offers with the result that all that is left is a natural life heading inexorably towards death.
Furthermore, as the biblical narrative as a whole tells us, and as Romans 5:12 specifically affirms, sin spread from Adam to all his descendants and where sin spread death spread as well. However, that is not the end of the story. As St. Paul goes on to say, ‘if many died through one man’s trespass, much more have the grace of God and the free gift in the grace of that one man Christ Jesus abounded for the many’ (Romans 5:15).
In Romans 5:15 ‘the many’ refers to humanity as a whole (it is equivalent to the ‘all men’ referred to in Romans 5:18) and the free gift to which St. Paul refers here is the gift of a right relationship with God (what the New Testament calls ‘righteousness’). This righteousness, he says, is bestowed upon the human race as a result of the obedience of Christ which reverses the effects of the disobedience of Adam. In the words of Romans 5:19, ‘For as by one man’s disobedience many were made sinners, so by one man’s obedience many will be made righteous.’
According to the New Testament ‘the one man Christ Jesus’ was God himself, God the Son, the second person of the Trinity, and his obedience consisted, as Lewis says, in living a human life marked by death to self.
The Christian tradition has focussed on Christ’s death on the cross as the climax of that death to self. Thus in his work On the Incarnation the great Eastern Church Father St Athanasius of Alexandria writes:
‘…. taking a body like our own, because all our bodies were liable to the corruption of death, He surrendered His body to death instead of all, and offered it to the Father. This He did out of sheer love for us, so that in His death all might die, and the law of death thereby be abolished because, having fulfilled in His body that for which it was appointed, it was thereafter voided of its power for men. This He did that He might turn again to incorruption men who had turned back to corruption, and make them alive through death by the appropriation of His body and by the grace of His resurrection. Thus He would make death to disappear from them as utterly as straw from fire.’
According to the New Testament, all that St. Athanasius says is true. In the words of St. Peter in 1 Peter 2:24 ‘He himself bore our sins in his body on the tree, that we might die to sin and live to righteousness.’ However, it also tells us that Christ’s death on the cross was only the culmination of a whole life marked by death to self. Whereas fallen human beings seek, as Lewis says, to do their own will, to control their own lives, Christ’s whole life was one in which his will was subordinated to the will of God the Father.
This is a point that is repeatedly made in John’s Gospel. Thus we are told in John 4:34 ‘Jesus said to them ‘My food is to do the will of him who sent me and to accomplish his work,’’ in John 5:30 Jesus declares ‘I seek not my own will but the will of him who sent me, in John 6:38 Jesus states ‘For I have come down from heaven not to do my own will, but the will of him who sent me’ and finally in john 8:29 Jesus tells the Pharisees ‘And he who sent me is with me: he has not left me alone, for I always do what is pleasing to him.’
If we enquire what was the Father’s will to which Christ was exclusively obedient the answer the New Testament gives was that Christ, the Son of God, came as a human being (the ‘Son of Man’) to ‘seek and to save the lost’ (Luke 19:10). He did this by dying and rising again, but also by his previous ministry in which he proclaimed God’s coming kingdom through word and deed and announced to his hearers that they might be part of this kingdom if they would but repent and believe the good news (Mark 1:15).
As Lewis says, this whole ministry, and not just the death at the end of it, was marked by suffering and enduring this suffering rather than taking the short cuts offered to him by the Devil (see Matthew 4:1-11) was a necessary part of that life of obedience which reached its climax on the Cross. In the words of John Calvin it was ‘the whole course of his obedience’ that made our salvation possible. If at any point in his life Christ had put himself first, given way to temptation, and committed sin, then his death, whatever form it took, would simply have been the natural and inevitable consequence of his sin. It would not have been the final defeat of sin and death that opened the way to the resurrection.
It is because Christ put God first and lived a life of perfect obedience throughout his life that his death was in reality the final defeat of the power of sin, and hence the defeat of death, and hence followed by the resurrection since death, being defeated, no longer had the power to hold him in the grave (Acts 2:24).
As we have seen, Lewis talk about the benefits of Christ’s saving activity in terms of a ‘good infection’ which we ‘catch’ from him. This is his illustration for what the New Testament talks about when it refers to our being ‘justified by faith’ (Romans 5:1), or when it says that all who have faith in Jesus Christ receive eternal life (John 3:16).
This is because in biblical terms faith unites us to Christ and thus enables us to receive the new life which he made possible through his life of perfect obedience. Martin Luther helpfully explains this point by saying that faith unites the believer with Christ as a bride is united with her bridegroom in marriage (Ephesians 5:31-32):
‘Christ is full of grace, life, and salvation. The soul is full of sins, death, and damnation. Now let faith come between them and sins, death, and damnation will be Christ’s, while grace, life, and salvation will be the soul’s; for if Christ is a bridegroom, he must take upon himself the things which are his bride’s and bestow upon her the things that are his. If he gives her his body and very self, how shall he not give her all that is his? And if he takes the body of the bride; how shall he not take all that is hers?
Here we have a most pleasing vision not only of communion but of a blessed struggle and victory and salvation and redemption. Christ is God and man in one person. He has neither sinned nor died, and is not condemned, and he cannot sin, die, or be condemned; his righteousness, life, and salvation are unconquerable, eternal, omnipotent. By the wedding ring of faith he shares in the sins, death and pains of hell which are his bride’s. As a matter of fact, he makes them his own and acts as if they were his own and as if he himself had sinned; he suffered, died, and descended into hell that he might overcome them all. Now since it was such a one who did all this, and death and hell could not swallow him up, these were necessarily swallowed up by him in a mighty duel; for his righteousness is greater than the sins of all men, his life stronger than death, his salvation more invincible than hell. Thus the believing soul by means of the pledge of his faith is free in Christ,its bridegroom, free from all sins, secure against death and hell and is endowed with the eternal righteousness, life and salvation of Christ its bridegroom.’
It is important to note that what Christ achieved through his incarnate obedience was not simply negative. It was not just the defeat of sin and death. Rather, as Lewis says, what he achieved opened up the possibility of sharing the eternal spiritual life which the Son of God has always possessed as the second person of the Trinity. In the New Testament this idea is expressed in 2 Peter 1:4 in terms of our becoming ‘partakers of the divine nature’ and elsewhere as our being adopted as the ‘children’ or ‘sons’ of God and our being ‘conformed to the image of his Son, in order that we might be the first born among many brethren’ (John 1:12, Romans 8:14-17, 8:23, 8:29, Galatians 4:4-7, 1 John 3:1-2).
As Calvin says, what this language teaches us is that ‘the end of the Gospel is to render us conformable to God, and so to speak, to deify us.’  In the words of Charles Cranfield, this does not mean ‘that we shall become gods or be absorbed into God.’ What it does mean is that ‘without ceasing to be men, without becoming divine, we shall share in that which is characteristically God’s own, the glory, perfection, blessedness and immortality of his life: or, to put it in other words, that we who are now ‘heirs of God, and joint heirs with Christ’ (Romans 8:17) shall eventually enter into possession of our inheritance. 
What we have seen taught by Lewis, and confirmed by the Bible, is that we are saved from sin and death through the perfect, lifelong, obedience of Christ. This obedience, which involved a life of suffering culminating in the crucifixion, put to death the inclination to self-centred rebellion against God inherent in our fallen human natures. It therefore defeated sin, and death which is the fruit of sin, and made possible the enjoyment of that eternal life in relationship with God which God always willed for his human creatures. What Christ did opens up the opportunity for salvation for the entire human race, but for any individual to benefit from it they have to catch the new life which Christ has made possible by being united with him through faith.
For all this to be true, however, Christ had to be God incarnate. In Luther’s words he had to be ‘God and man in one person.’
He had to be God because first of all, the universal corruption of human nature meant that human beings were unable to save themselves. As St. Paul notes, even direct instruction from God through the Jewish law was not able to turn fallen humanity away from the path of sin and death. All it could do was make known to people how sinful they were (Romans 3:20, 7:7-25). This being the case, what was required to save humanity was power coming from outside.
Furthermore, in order that human beings should not only be freed from sin and death, but enabled to become children of God and partakers of the divine nature, that outside power had to be the power of God himself. To use Lewis’ terminology, it is only because Christ is the Son of God and therefore possesses the ‘begotten life’ that he is able to give us the ‘begotten life’ as well. Were he not God he could not do this. No creature could do this. No angel could do this. Only God himself could do this. Only God can share his own life with us.
Christ also had to be human. He had to unite our humanity to himself both in order defeat sin and death through his life of perfect human obedience and he had to unite our humanity to himself so that through that union we might be united to the life of God. As St. Basil of Caesarea put it:
‘If, then, the sojourn of the Lord in flesh has never taken place, the Redeemer paid not the fine to death on our behalf, nor through Himself destroyed death’s reign. For if what was reigned over by death was not that which was assumed by the Lord, death would not have ceased working his own ends, nor would the sufferings of the God-bearing flesh have been made our gain; He would not have killed sin in the flesh: we who had died in Adam should not have been made alive in Christ; the fallen to pieces would not have been framed again; the shattered would not have been set up again; that which by the serpent’s trick had been estranged from God would never have been made once more His own. 
Why the birth of Christ is the Christmas ‘must have.’
What he have looked at in this post shows us why the birth of Christ is the Christmas ‘must have’. As human beings we can get by quite happily with the things that are sold by Marks and Spencer and other similar retailers. Having what they sell is not a necessary part of our human existence.
However, in order for us to achieve the end for which God created us we do need Christ to have become incarnate, and therefore for the birth in Bethlehem to have taken place. Without the incarnation and the birth that was an integral part of it we would have remained trapped forever by our fallen natures, unable to defeat sin and death and unable to share the life of God. Only the Son of God taking our humanity upon himself enabled these things to happen. For that reason his birth is the one essential ‘must have’ for all human beings, not only at Christmas, but always. We don’t need Christmas lights, parties and gifts, but we do need Jesus Christ and Christians are right to celebrate his birth.
M B Davie 12.12.18
 C S Lewis, Mere Christianity, Glasgow: Fount, 1984, p. 151.
 Ibid, pp.151-2.
 Ibid, p.152,
 Ibid, p.52.
 Ibid, pp.153-4.
 St. Athanasius, On The Incarnation, 2:8-9 at http://www.onthewing.org/user/Athanasius%20-%20On%20the%20Incarnation.pdf
 John Calvin, Institutes of the Christian Religion, BK II.16.5, Grand Rapids: Eerdmans, 1975, p.437.
 Martin Luther, The Freedom of a Christian, in Martin Luther, Three Treatises, Philadelphia: Fortress Press, 1978, pp.286-287.
 John Calvin on 2 Peter 1:4, cited in C E B Cranfield, I and II Peter and Jude, London: SCM, 1960, p. 176.
 Ibid, p.176.
 St Basil of Caesarea, Letter CCLXI.2 in The Nicene and Post Nicene Fathers, second series, vol, VIII,Edinburgh and Grand Rapids, T&T Clark/Eerdmans, 1996, p. 300.