At the heart of Christmas is the celebration of the miracle that took place when Jesus was conceived in the womb of the Virgin Mary. In this article I shall explore three issues in relation to this miracle, the nature of the miracle, how this miracle fits in with the way God normally operates in the world, and why the miracle took the form that it did.

Starting with the nature of the miracle, the first thing to be noted is that what we are talking about, according to the biblical account, is a virginal conception rather than a virgin birth. There is nothing in Luke's account of Jesus' birth (Luke 2:1-7) that says there was anything miraculous about the birth itself. What was miraculous was how Jesus was conceived and the person that resulted from that conception.

The nature of that miracle is well summarised in the second of the Church of England's Thirty Nine Articles, 'Of the Word, or Son of God which was made very Man,' This states:

"The Son, which is the Word of the Father, begotten from everlasting of the Father, the very and eternal God, and of one substance with the Father, took man's nature in the womb of the blessed Virgin, of her substance: so that two whole and perfect natures, that is to say, the Godhead and manhood, were joined together in one person, never to be divided, whereof is one Christ, very God and very man, who truly suffered, was crucified, dead, and buried, to reconcile His Father to us, and to be a sacrifice, not only for original guilt, but also for all actual sins of men."

What this statement tells us is two things:

• That the eternal Son of God, the second person of the Trinity, united to himself in the womb of the Virgin Mary a human nature derived from Mary.
• The result was that from that point onwards Jesus Christ, the Son of God, was a person who possessed two natures, the divine nature which he possessed from eternity and the human nature which he possessed from the moment of its conception in Mary's womb.

If we ask how the actual act of human conception took place the answer that the Bible gives us is that it was through the action of the Holy Spirit. Thus, in Matthew 1:20 the angel of the Lord tells Joseph 'that which is conceived in her [Mary] is of the Holy Spirit.' Likewise, in Luke 1:35 the Angel Gabriel tells Mary:

"The Holy Spirit will come upon you, and the power of the Most High will overshadow you; therefore the child to be born will be called holy, the Son of God."

To quote the seventeenth century writer John Pearson, believing in the Christmas Miracle therefore means believing:

"...that the Word was in this manner made flesh, that he was really and truly conceived in the womb of a woman, but not after the manner of men; not by carnal copulation, not by the common way of human propagation, but by the singular, powerful, invisible, immediate operation of the Holy Ghost, whereby a Virgin was beyond the law of nature enabled to conceive, and that which was conceived in her was originally and completely sanctified."

Moving on to the second issue, how the Christmas miracle fits in with how God normally operates in. the world, it is sometimes argued that the miraculous nature of Jesus' conception calls his true humanity into question. As CS Lewis argues in his book on miracles, this argument fails to note that what happened to Mary is not out of line with how God normally operates, since in reality all acts of conception are in fact acts of God. In his words:

"The human father is simply an instrument, a carrier, often an unwilling carrier, always simply the last in a long line of carriers – a line that stretches far beyond his ancestors into pre-human and pre-organic deserts of time, back to the creation of matter itself. That line is in God's hand. It is the instrument by which He normally creates a man. For He is the reality behind both Genius and Venus; no woman ever conceived a child, no mare a foal, without Him. But once, and for a special purpose, He dispensed with that long line which is His instrument: once His life-giving finger touched a woman without passing through the ages of interlocked events. Once the great glove of Nature was taken off His hand. His naked hand touched her."

As Lewis goes on to say, like the other nature miracles recorded in the gospels:

"...the miraculous conception is one more witness that here is Nature's Lord. He is doing now, small and close, what He does in a different fashion for every woman who conceives. He does it this time without a line of human ancestors: but even when He uses human ancestors it is not the less He who gives life. The bed is barren where that great party, Genius, is not present."

Because, as Lewis argues, what we see in the birth of Christ is what is fundamentally true of all births, namely, that they are the result of the creative activity of God bringing new life into being in the body of a woman, it follows that what happened in the case of the birth of Christ cannot call His true humanity into question. If the action of God means that Christ was not truly human then this means that no other baby is truly human either (a position which no one has yet sought to defend).

If we ask why God chose to bring about Jesus' birth in the particular miraculous way that he did, the first thing to note is that God was under no necessity to bring about Jesus' conception through a miracle. Even if the conception had taken place as the result of marital intercourse between Mary and Joseph there would still have been a human nature which God the Son could have taken upon himself at the moment of its conception. It is sometimes suggested that a virginal conception was necessary to stop Jesus inheriting original sin, but this argument does not work because original sin is not passed on exclusively down the male line. Mary would have passed on original sin just as much as Joseph and Mary together.

As Pearson notes, what made Jesus 'originally and completely sanctified' was not the absence of a human father, but the positive sanctifying action of the Holy Spirit. To quote the words of the angel Gabriel to Mary once again, it is the fact that 'The Holy Spirit will come upon you,' that means that 'the child to be born will be called holy, the Son of God.'

So, if God was under no necessity to perform this miracle, then why did he do so? To answer this question, it is important to understand that in the New Testament individual miracles act as signs pointing to wider truths. Thus, the miracle of the feeding of the five thousand tells us that Jesus provides us with the spiritual sustenance we need, the miraculous healing of the blind tells us that Jesus is the one who enables the spiritually blind to see, and the raising of the dead tells us that Jesus is the one who gives us eternal life.

In similar fashion the miracle of Jesus' virginal conception points us to two wider truths, one negative and one positive.

The negative truth to which the miracle points is that the mystery of human salvation is the result of God's work and not ours. In the miracle of the virginal conception, human striving and activity are set aside in favour of the activity of God to signify the truth that human beings cannot save themselves. To quote the Swiss theologian Karl Bath, what the miracle reminds us of is that:

"Of course, Man is involved, but not as God's fellow-worker, not in his independence, not with control over what is to happen, but only –and even that because God has presented him with Himself – in his readiness for God. So thoroughly does God judge sin in the flesh by being gracious to Man. So much does God insist that He alone is Lord by espousing the cause of man. This is the mystery of grace to which the natus ex virgine points. The sinful life of sex is excluded as the source of the human existence of Jesus Christ, not because of the nature of sexual life nor because of its sinfulness, but because every natural generation is the work of willing, achieving, creative, sovereign man. No event of natural generation will be a sign of the mystery indicated here."

The positive truth is that what takes place in the conception of Jesus is a prototype of what happens to Christians subsequently. In his conception human nature is made open to God, and therefore participates in God's holiness, through the work of the Holy Spirit, and this is what happens to Christians as well. In their case too, it is the work of the Spirit that gives them 'the power to become children of God' (John 1:13) . To quote Barth again, what Jesus' miraculous conception tells us is that:

"Through the Spirit it becomes really possible for the creature, for Man, to be there and to be free for God. Through the Spirit flesh, human nature, is assumed into unity with the Son of God."

To summarise, the miracle we celebrate at Christmas is that as a result of the action of the Holy Spirit Mary conceived a human nature that was assumed by God the Son, thus forming the God-Man Jesus Christ. This miracle is in line with God's action in bringing about all human births and the particular form it took tells us that human beings cannot save themselves, but that God can and does make us his children through the work of the Holy Spirit.