We don't use the words begetting or begotten much in modern English, but everyone still knows what they mean. To beget is to become the father of: to create is to make. And the difference is this. When you beget, you beget something of the same kind as yourself. A man begets human babies, a beaver begets little beavers and a bird begets eggs which turn into little birds. But when you make, you make something of a different kind from yourself. A bird makes a nest, a beaver builds a dam, a man makes a wireless set-or he may make something more like himself than a wireless set: say, a statue. If he is a clever enough carver he may make a statue which is very like a man indeed. But, of course, it is not a real man; it only looks like one. It cannot breathe or think. It is not alive. Now that is the first thing to get clear. What God begets is God; just as what man begets is man. What God creates is not God; just as what man makes is not man. That is why men are not Sons of God in the sense that Christ is. They may be like God in certain ways, but they are not things of the same kind. They are more like statues or pictures of God. (Mere Christianity – Lewis, Chapter 23 “Making and Begetting”).
To beget, however, is to call something into existence; to father something; to produce something. Remember all those “begets” in the beginning pages of the Bible? That’s what they were doing. You are of the same substance as your father; you were not created as a sculptor makes a stature out of stone. You were produced “through the will of man” (your parents) “through the will of the flesh” (sexual intercourse). So, for John to call Jesus “the only-begotten”, is a profound thing. To be clear, I don’t’ believe John is saying that the Son was produced as a result of sexual intercourse, but that the Son was produced of the same substance as the Father – both divine, almighty God. The Son is begotten of the Father – the only being who so exists. He was also, by virtue of the fact that He is deity, “with God in the beginning.” The point is that He was not a created being like we human beings. Jesus, as John tells us in v. 14, assumed the human nature in the womb of the Blessed Virgin Mary. There, in the virgin’s womb, the divine and human natures were inseparably joined in one person, Jesus, the God-man (AC III 1-2).
St. Paul expands on this in his letter to the Philippians:
John introduces us to Jesus, the God-man, in the first sentences of his Gospel, and in doing so, shows us a shadow of the triune nature of God. In a handful of sentences, John tells Jew and Gentile, in the beginning of his gospel, the Word came, but many, especially the Jews, rejected Him because they did not recognize Him. Jesus says of the Pharisees “You diligently study the Scriptures because you think that by them you possess eternal life. These are the Scriptures that testify about me, yet you refuse to come to me to have life” (John 5:39-40). Not only did Jesus fulfill the Old Testament messianic prophecies, which we will see as we study the Gospel of John, but he was also doing the things the Pharisees expected the Messiah to do when he came, yet they rejected Him.
Who do we say that Jesus is? Jesus asked this question of Peter and he rightly answered, “You are the Christ, the Son of the living God” (Matt. 16:16). It was on the rock of Peter’s confession that Jesus built His Church. Peter, by the Power of the Holy Spirit, could see what the Pharisees had hardened their hearts against, even though he didn’t have a full understanding of all the implications. Jesus was not a political “savior,” come to restore Israel, as the elite Jewish Pharisees and Teachers of the Law expected. He was not simply a virtuous man or good teacher. Jesus of Nazareth is the Christ – the Son of God – who fulfilled all the prophecies of scripture and, by His death and resurrection, atoned for the sin of mankind and purchased us from death and the devil by his blood on the cross.