This passage highlights the two great moments in God’s plan of redemption, the missions of the Son and the Holy Spirit. In the incarnation, the Father sent the Son, while at Pentecost the Father sent the Spirit of his Son. These are trinitarian events, all three persons working together indivisibly, as in all the works of God. Their centrality points to the value of the church year in constantly reminding us of the foundations of the Christian gospel.
The incarnation took place at just the right time. It was planned by God from eternity. The context here in Galatians is the progress of the people of God from childhood in the OT to maturity now that Christ has come (Gal. 3:19, 23-25, 4:1-3).
God keeps his appointments.
The conception and birth of Jesus took place exactly at the time God chose. The Son died on the cross at Passover, not a day earlier, not a day later. The Spirit was sent 'when the time had fully come' (Acts 2:1), not a day earlier, not a day later, on the feast of Pentecost precisely. Jesus was born just as the Roman Empire had determined that a census should occur. God observes and honours the feasts he had appointed in Israel. In our own day the ministry of the Word and the sacraments are appointed by God and he honours them as well. The sacraments are first of all signs for God rather than us: in the Noachic covenant, God says 'when … the bow is seen in the clouds, I will remember my covenant' (Gen. 9:13-14). We have confidence that he will bless his arrangements.
This is an action of the indivisible trinity in eternity. Paul is accustomed to use theos (God) for the Father. The relational nature of the name underlines this point; 'his Son' entails the Father. The names denote identity of nature – the Son is of precisely the same nature as the Father. There is also an order; the Father sends, the Son is sent. The verb conjures up the idea of being sent to fulfil a mission in another place.
The engagement of the entire undivided trinity is clear too later in the section, where the Father is said to have sent the Spirit of his Son into our hearts (v. 6). Again, Paul describes the resurrection as brought about when “the Spirit of him [the Father] who raised Jesus [the Son] from the dead” (Rom. 8:11).
Paul wants to stress the Son’s humanity. His gestation and birth were exactly the same as any other gestation and birth - “born of a woman.” Jesus was born in the usual way.
However, note the verb Paul uses. Four times in this chapter, when referring to human generation he uses the verb one would expect – gennao (vv. 23, 24 x 2, 29) but here he uses ginomai, which means ‘to become’ or ‘to be made.’
Paul is aware that there was something unusual about the generation of Jesus.
Luke was one of his travelling party, a close colleague, and in his Gospel he recorded the visit of the angel Gabriel to the virgin Mary. Paul could hardly have been unaware of the account relating to the conception of Jesus by the Holy Spirit (Lk. 1:34-35). Yes, Jesus was born of the virgin Mary in the usual way but he was conceived by the Holy Spirit. We should speak of virginal conception rather than virgin birth. Indeed, any case of parthenogenesis could only produce a female, since the Y chromosome would be lacking. The Spirit provided that. So the Father sent the Son, conceived by the Holy Spirit.
Note the consequence.
The Son continues to be the Son after conception as before. However, he is now man. He has added human nature. He is still the Son but as the Son he now and for ever has a human body and soul in indivisible union. He lived under the conditions of humanity in a fallen and disordered world.
This meant that he, the creator of the universe, one of the Trinity, needed to be fed and changed by human parents, utterly dependent on them. His humanity was and is still unabbreviated, differing only in that he had no sin and did no sin. He ate, he drank, as a baby he vomited and did diahorrea, he dribbled and learned to speak, stammering in inarticulate sounds. Once I stressed this in a sermon, back in 1988 in the UK, and a man came up to me afterwards and denounced me as being disrespectful to our saviour. I replied that, far from it, if this were not so, you could not be saved. Your salvation depends on the fact that one of the trinity cried as a human baby, according to the flesh. If he had not done so he would not have been human and we would have no gospel, no hope.
Jesus was born a Jew. He was born into a scenario in which Israel was still in a state of minority. The time had not yet fully come. The law, Paul has said, was the 'guardian' to lead us to Christ. The Galatian church had been influenced by some Jewish Christians who had overstressed the law and had undermined the grace of the gospel. The Son came to redeem his people from the law, not from the moral law expressed in the decalogue but from the accumulation of ceremonies that Peter had said was greater than the people could bear (Acts 15:10). Jesus was born into a situation like that. He came to redeem his people, to deliver them, to free them from slavery by the payment of the price of his death on the cross.
The people of God were brought from childhood to maturity, from slavery to the onerous demands under which they had been placed to the inheritance of sonship. 'Sonship' is not a politically correct term these days but it highlights the point that our relation to God is now precisely the same as that of the eternal Son. He is Son by nature, we share this – female as well as male – by adoption. We can now call God 'our Father,' just as Jesus, uniquely as an individual, does. We do it in whatever language we speak. The text says abba which means 'father' in Aramaic, and pater meaning 'father' in Greek. We say the same, from every nation under heaven, made one in Christ. The Spirit of the Father’s Son enables us to express it.
The staggering thing about the incarnation is that the eternal Son of the Father lived as man from embryo to adulthood, took our place as a slave and a minor, in a world of disorder and hostility, so that we, enslaved to sin, might receive the sonship. He became weak that we might become strong. He who was rich for our sakes became poor that we through his poverty might become rich (2 Cor. 8:9). This is the message of the incarnation. This is the story of Christmas. This is the hope of the world.
Robert (Bob) Letham is Professor of Systematic and Historical Theology at Union School of Theology. He is the author of numerous theological books, including The Work of Christ in the Contours of Christian Theology series.