The most celebrated critical commentary on the birth narratives is that of Raymond Brown – The Birth of the Messiah.

In discussing the birth narratives as history, Brown cites two sets of problems:

1. The problem of corroborating witnesses

Regarding the main body of the Gospel narratives, there is no shortage of witnesses whose reminiscences could be harvested.  And there was a tradition that had been passed down from this first witnesses.  See Acts 1:22; 1 Cor 15:3 etc.

But how do we know what happened at Jesus’ birth?  None of the disciples was around.  There is no evidence of a tradition that had been passed down to the early church (which is, accordingly, virtually silent on the matter of Jesus’ birth).

The guess that Joseph was the source of the Matthean birth material is not persuasive.  Joseph makes no appearance during Jesus’ adult ministry, and he had probably died some time earlier.  Mary is a more likely source of information, given that she was part of the post-resurrection community (Acts 1:14).  This would make it plausible that she was a source for Luke’s first two chapters (which emphasise the role of Mary).  But it does not account for the infancy material in Matthew (which focusses on Joseph).  It has been conjectured that James, the brother of our Lord, might have been a source for Matthew’s early material; but there is no real evidence for this.

2. The problem of conflicting details

To be sure, Matthew’s and Luke’s account have many points in common:

a) The parents to be are Mary and Joseph who are legally engaged or married, but have not yet come to live together or have sexual relations (Matt 1:18; Luke 1:27, 34).
b) Joseph is of Davidic descent (Matt 1:16, 20; Luke 1:27, 32; 2:4).
c) There is an angelic announcement of the forthcoming birth of the child (Matt 1:20–23; Luke 1:30–35).
d) The conception of the child by Mary is not through intercourse with her husband (Matt 1:20, 23, 25; Luke 1:34).
e) The conception is through the Holy Spirit (Matt 1:18, 20; Luke 1:35).
f) There is a directive from the angel that the child is to be named Jesus (Matt 1:21; Luke 1:31).
g) An angel states that Jesus is to be Savior (Matt 1:21; Luke 2:11).
h) The birth of the child takes place after the parents have come to live together (Matt 1:24–25; Luke 2:5–6).
i) The birth takes place at Bethlehem (Matt 2:1; Luke 2:4–6).
j) The birth is chronologically related to the reign (days) of Herod the Great (Matt 2:1; Luke 1:5).
k) The child is reared at Nazareth (Matt 2:23; Luke 2:39).

But there are many striking differences:

‘The genealogy in Matt 1:1–17 is very unlike the genealogy that Luke has placed outside the infancy story (3:23–38). The whole of Matt 2:2–22 has no parallel in Luke, just as most of Luke 1 (outside 1:26–35) and most of Luke 2 have no parallel in Matthew.

The Lucan account alone depicts the following: the story of Elizabeth, Zechariah, and the birth of JBap; the census which brings Joseph to Bethlehem; the acclamation of Jesus by the shepherds; the presentation of Jesus in the Temple as the parents return to Nazareth; and the loss and finding of Jesus in the Temple at the age of twelve.

Matthew concentrates on a different series of happenings of which Luke makes no mention: the star, the magi, Herod’s plot against Jesus, the massacre of the children at Bethlehem, and the flight into Egypt.’

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But (continues Brown) the two narratives are not of different from one another; they conflict with one another at a number of points:

‘According to Luke 1:26 and 2:39 Mary lives in Nazareth, and so the census of Augustus is invoked to explain how the child was born in Bethlehem, away from home. In Matthew there is no hint of a coming to Bethlehem, for Joseph and Mary are in a house at Bethlehem where seemingly Jesus was born (2:11). The only journey that Matthew has to explain is why the family went to Nazareth when they came from Egypt instead of returning to their native Bethlehem (2:22–23).’

Furthermore:

‘Luke tells us that the family returned peaceably to Nazareth after the birth at Bethlehem (2:22, 39); this is irreconcilable with Matthew’s implication (2:16) that the child was almost two years old when the family fled from Bethlehem to Egypt and even older when the family came back from Egypt and moved to Nazareth. Of the options mentioned before we made the detailed comparison of the two narratives, one must be ruled out, i.e., that both accounts are completely historical.’

Matthew’s account includes a number of extraordinary details that, if historical, ‘should have’ left a trace, either in the Jewish records or in the rest of the New Testament.  These include the story of the Magi and the star, and the reaction of Herod and ‘all Jerusalem’, and his subsequent slaughter of the baby boys.

Luke’s reference to a general census under Augustus is ‘almost certainly wrong’.

A number of these scenes, implausible as history, are better viewed as re-writings of Old Testament stories:

‘For instance, Matthew’s story of the magi who saw the star of the Davidic Messiah at its rising is an echo of the OT story of Balaam, a type of magus from the East, who saw the star rise out of Jacob (§ 6, C2). The story of Herod seeking the life of the infant Jesus and massacring the male children at Bethlehem is a reapplication of the OT story of the wicked Pharaoh who sought the life of the infant Moses and slaughtered the male children of the Israelites, even as the story of Joseph, the father of Jesus, who dreams dreams and goes to Egypt is a reapplication of the story of the patriarch Joseph who does the same thing (§ 4, B2). Luke’s description of Zechariah and Elizabeth, the parents of JBap, is taken, at times almost verbatim, from the OT description of Abraham and Sarah.’

I turn now to this article, by James Bejon.  He thinks that neither Matthew nor Luke was attempting a blow-by-blow account of our Lord’s birth.  Rather, each Evangelist was intent on selecting, from the many available historical details, those which highlighted his own theological emphasis.  So:

‘Jesus was born in tumultuous times. The events of his birth included a census, a massacre, a flight to Egypt, and many other things besides, and Matthew and Luke took these events to be significant—i.e., to frame Jesus as the fulfilment of Biblical history—but each writer focused on different aspects of them.

‘For Matthew, Jesus is a Moses-like deliverer, who presents an immediate threat to the world’s Herods. As far as Matthew is concerned, then, Jesus’ presentation at the Temple and childhood in Nazareth are irrelevant, and to include them would be a distraction.

‘Meanwhile, for Luke, Jesus is a more subversive and Samuel-like figure, who grows up and in around the Temple. From Luke’s perspective, then, Jesus’ stay in Bethlehem (after his presentation at the Temple) and flight to Egypt are irrelevant, while his presentation at the Temple and (undramatic) childhood are highly relevant.’

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Just as Brown does, Bejon recognises a number of common elements in the two accounts.  But, again like Brown, he acknowledges the various differences:

‘Whereas Matthew tells us about Herod, the wise men, the massacre at Bethlehem, and the flight to Egypt, Luke tells us about a different set of events altogether—events which involve Caesar, the shepherds, Jesus’ presentation at the Temple, and Jesus’ childhood in Nazareth.’

Hence the questions about historical reliability:

‘If Luke was a competent historian, wouldn’t he have been aware of the massacre of Bethlehem’s infants? And, if he was aware of it, why didn’t he mention it? Why does Luke instead have the family head back to Nazareth, with no mention of Joseph’s flight to Egypt? And why, if Luke’s narrative is reliable, doesn’t Matthew mention Caesar’s decree and/or the shepherds? Is it credible to think Matthew was aware of the events recorded in Luke’s narrative and yet declined to mention them (and vice-versa in Luke’s case)?’

The answer to such questions depends, accordng to Bejon, on what we think about how and why the Gospels were written.  Are we to assume that each Evangelist set about recording everything he knew?  Are we to suppose that if Matthew mentions A but Luke does not mention it, the latter is ignorant of it?  (Such questions become even more insistent if we apply them to John’s Gospel: do we think that John was unaware of Jesus’ temptations, baptism, parables, exorcisms, transfiguration and institution of the Lord’s Supper because he doesn’t mention them?

This leads us to consider the distinctive purposes of Matthew and Luke.

Matthew tells us about Herod’s panic, the magi and their gifts, the slaughter of the infants and the flight to Egypt.  These are all reminiscent of the exodus.  Accordingly, Matthew is presenting Jesus’ birth as herlading an exodus-to-come.

More fully:

‘Both stories open with Israel ruled by a foreign overlord (in one case an Egyptian, in the other an Edomite). Both revolve around the birth of a child who’s destined to deliver his people. In both cases, the overlord in question views the child as a threat (cp. Exod. 1.9–10). Both stories have the overlord massacre Israel’s infants in an attempt to secure his position. In both stories, God’s deliverer flees to a foreign land, where he holes out until his enemies have passed away (cp. Matt. 2.20 w. Exod. 4.19). In both stories, God outwits (ἐμπαίζω) his enemies (cp. Matt. 2.16 w. Exod. 10.2). And, in both stories, God’s people are made rich by the Gentiles (cp. Egypt’s wealth w. the wise men’s gifts).’

Matthew himself makes the connects explicit with his quotation, in Mt 2:15, of Hos 11:1 – “Out of Egypt I called my son.”  God is once again calling forth his Son from Egypt to begin an even greater work of deliverance.

But the exodus instigated by Jesus will be a different type of exodus.  This is underscored by the back-to-front nature of the new story:

‘The murderous king isn’t an Egyptian Pharaoh, but a ‘king of the Jews’. The land in which God’s son is imperilled isn’t Egypt, but Israel. And the land where the son is accepted isn’t Israel, but Egypt. Why? Because Jesus’ exodus won’t simply be a rerun of the original; it will be a different kind of exodus. The line of division between God’s people and God’s enemies won’t be drawn on the basis of nationality (Israel vs. Egypt: Matt. 8.11–12, 10.34–39), but on the basis of obedience (12.46–50). And, on the night of the Passover to come, God’s firstborn Son won’t escape death.’

(Bejon also detects both an exodus theme and a Gentile theme in Matthew’s genealogy, and but I shall pass over these for the present.)

For Matthew to have imported historical details from Luke would have made his own narrative far less cohesive.  Caesar’s involvement, for example, is irrelevant to this exodus theme, whereas Herod is central to it.

Luke tells us about Caesar’s census, the shepherds, the presentation at the temple, and Jesus’ childhood in Nazareth.

In short, whereas Matthew presents Jesus as a Davidic King, Luke emphasises his more lowly priestly origins and role.

More fully:

• Whereas Matthew’s Gospel opens with an announcement of Jesus’ status as the long-awaited son of David (1.1), Luke’s opens with a story about the struggles of a little-known priestly couple and their duties at the Temple.

• Whereas Matthew’s genealogy is headed up by two of the best known figures in Jewish history (Abraham and David) (1.1), Luke’s begins in obscurity and works its way upwards to David and Abraham—a direction of travel elsewhere associated with priestly genealogies (cp. 1 Chr. 6.31–48 w. its context).

• Whereas Matthew’s narrative begins in Bethlehem, Luke’s begins in the Judean hill-country and later relocates to Nazareth—a town of little significance in OT history (John 1.46).

• Whereas Matthew’s Messiah is born king of the Jews (Matt. 2.2), Luke’s begins his ministry at the age of thirty (as all priests do).

• Whereas Matthew’s birth narrative culminates in the declaration ‘The kingdom of heaven is at hand!’ (Matt. 3.1–2), Luke’s culminates in a description of Jesus’ worship at the Temple (and submission to his parents).

• And, whereas Matthew has Jesus offered ‘the kingdoms of the world’ at the conclusion of his temptations, Luke has Jesus brought to the Temple, which is where his Gospel ultimately winds up.

The details that Luke records add up to a recapitulation of the birth narrative of Samuel (1 Sam 1-2).  If for Matthew Jesus was a Moses-like leader, Luke presents him as a Samuel-like servant.  Like Samuel, Jesus was left at the temple, astounded the wise, and grew in favour with God and man.

Consistent with this picture of Jesus painted by Luke is this Evangelist’s association of Jesus with the poor:

‘While Matthew has Joseph reside in a house, Luke has him lodge in a guestroom. While Matthew has Jesus visited by wise men, Luke has him visited by (mere) shepherds. And, while Matthew has Jesus given gold and precious spices, Luke has him taken to the Temple along with a poor man’s sacrifice (cp. Lev. 12.8).’

Then, as Luke unfolds his story:

‘The Gospel is fundamentally for the poor and downtrodden (Lk 3.5–6, 4.18, 7.22, 14.11, etc.). Jesus has come to inaugurate a Jubilee—a ‘year of favour’, a time when those who have lost their inheritance are given new hope (Lk 4.18–19)’

Just as it didn’t suit Matthew’s purpose to include the census, so it didn’t suit Luke’s to record the slaughter of the boys.  (If he had done that, he would also have had to tell us about the magi and the flight to Egypt).

It is apparent, then, that

‘Luke is interested in the lower profile aspects of Jesus’ infancy—in the nearby shepherds rather than the shepherd-king of Micah 5.2, in the Temple rather than the palace, and in Nazareth rather than Bethlehem.’

We conclude, then, that the birth narratives of Matthew and Luke are different for good reasons.  Although none of this proves that they both historically accurate in every detail, we now have good reasons for thinking that it was selectivity, rather than ignorance (or fabrication) that led them to pen their respective accounts as they did.