Demolishing Triablogue, part 5: The Virgin Birth and Mark 6:3

Jason Engwer argues that the failure to mention Joseph as Jesus father in Mark 6:3 is more consistent with the theory that there was something peculiar about Jesus' birth, than with any other theory.

NAU  Mark 6:1 Jesus went out from there and came into His hometown; and His disciples followed Him.
 2 When the Sabbath came, He began to teach in the synagogue; and the many listeners were astonished, saying, "Where did this man get these things, and what is this wisdom given to Him, and such miracles as these performed by His hands?
 3 "Is not this the carpenter, the son of Mary, and brother of James and Joses and Judas and Simon? Are not His sisters here with us?" And they took offense at Him.
 4 Jesus said to them, "A prophet is not without honor except in his hometown and among his own relatives and in his own household."
 5 And He could do no miracle there except that He laid His hands on a few sick people and healed them. (Mk. 6:1-5 NAU)

Engwer's biggest oversight is Mark's failure to say anything explicit about the virgin birth, if indeed Mark says what he does in 6:3 because of a scandal that ultimately arises from Jesus being born of a virgin.

Engwer will say Mark didn't feel the need to repeat what his originally intended audience already believed or accepted, but on the contrary, early patristic testimony asserted that Mark's purpose was no less than to repeat for his church, at their request, what they heard Peter preach.  From Eusebius, H.E. 6:14, Schaff edition:

Again, in the same books, Clement gives the tradition of the earliest presbyters, as to the order of the Gospels, in the following manner: The Gospels containing the genealogies, he says, were written first. The Gospel according to Marks had this occasion. As Peter had preached the Word publicly at Rome, and declared the Gospel by the Spirit, many who were present requested that Mark, who had followed him for a long time and remembered his sayings, should write them out. And having composed the Gospel he gave it to those who had requested it.

So Engwer cannot explain Mark's failure to explicitly mention the virgin birth on the theory that Mark trusted that his readers already accepted this doctrine.  Because they were already converts and a church, they clearly had accepted all major teachings Peter gave them, yet Mark is precisely repeating for them in written form that which they previously heard and believed.  So Engwer's presumption that the author of Mark either knew about or accepted the virgin birth story, but for some mysterious reason never quite got around to mentioning it, is quite strange:  The virgin birth, if true, would certainly strongly support, at least for Christians, their belief that Jesus was the promised messiah.  Yet Engwer would have the reader believe that Mark never thought such a strong supporting bit of history/doctrine worthy to be explicitly mentioned?

Engwer wastes his readers time arguing for such a trifling thing, because Jesus, when presented with an opportunity to say something good about his mom or his birth, declined to do so:

27 While Jesus was saying these things, one of the women in the crowd raised her voice and said to Him, "Blessed is the womb that bore You and the breasts at which You nursed."
 28 But He said, "On the contrary (Greek: men), blessed are those who hear the word of God and observe it." (Lk. 11:27-28 NAU)

Louw-Nida indicate that in the Greek, "contrary" signaled disagreement with the former speaker:

89.128  μενοῦν ; μενοῦνγε: relatively emphatic markers of contrast - 'but, on the contrary, on the other hand.' μενοῦν: μενοῦν μακάριοι οἱ ἀκούοντες τὸν λόγον τοῦ θεοῦ καὶ φυλάσσοντες 'on the contrary, those who hear the word of God and keep it are happy' or '... fortunate' Lk 11.28. For other interpretations of μενοῦν in Lk 11.28 , see 89.50 and 91.8. μενοῦνγε: μενοῦνγε σὺ τίς εἶ ὁ ἀνταποκρινόμενος τῷ θεῷ 'on the contrary, who are you to talk back to God?' Ro 9.20.

So Jesus was not simply reminding people of the higher priorities, he was disagreeing with the female speaker's assumption that the blessedness of his mother had any relevance to anything concerning the gospel.

Oh, did I mention?  Jesus also never brought up the subject of his birth.

I answer Engwer in point by point fashion here, since he or somebody at Triablogue is apparently too frightened of my scholarly answers to them and have banned me, while dishonestly leaving up their replies to me. 

Thursday, December 05, 2013

Posted by Jason Engwer at 5:31 AM

Jesus' Childhood Outside The Infancy Narratives (Part 5): Mark

Mark's gospel, like Matthew and Luke, has John anticipating Jesus' ministry before it begins (1:2-8).

As in the other gospels, Mark has John popularly received early on (1:5). See my comments earlier about the significance of John's reception.

Mark's accounts of the calling of the disciples (e.g., 1:16-20) are similar to what we find in Matthew. See my earlier comments in my post about Matthew's gospel.

The infancy theme of Jesus' background in Nazareth is mentioned by Mark (1:24).

Mark 1:24 neither expresses nor implies the least little bit about Jesus' infancy, it merely indicates that somebody believed Jesus to have been from Nazarteth, whether he was actually born there is hardly at issue:

 23 Just then there was a man in their synagogue with an unclean spirit; and he cried out,
 24 saying, "What business do we have with each other, Jesus of Nazareth? Have You come to destroy us? I know who You are-- the Holy One of God!"
 25 And Jesus rebuked him, saying, "Be quiet, and come out of him!" (Mk. 1:23-25 NAU)

 Conservative Inerrantist Evangelical scholar J.A. Brooks says absolutely nothing about Jesus' infancy in his commentary on Mark 1:24:

1:24 The questions sought to put Jesus on the defensive and force him to justify his action (cf. Judg 11:12; 2 Sam 16:10; 1 Kgs 17:18; 2 Kgs 3:13; 2 Chr 35:21). The second sentence, however, could be an assertion rather than a question: “You have come to destroy us!” The demon tried unsuccessfully to oppose Jesus by employing his name. Note how the demon spoke through the man, sometimes for himself and sometimes for demons in general. “Holy One of God” probably is a messianic title, although there is very little attestation for that. In the Old Testament God is usually the Holy One. Here the title implies that Jesus has a special relationship with God. In v. 24 the demon acknowledged the true identity of Jesus (cf. v. 34)—something the disciples were slow to do. In fact, only at the crucifixion did a human being confess Jesus as the Son of God, and he was not one of the disciples (15:39).

Brooks, J. A. (2001, c1991). Vol. 23: Mark (electronic e.). Logos Library System;
The New American Commentary (Page 51). Nashville: Broadman & Holman Publishers.

 Asserting that the demon spoke the true identity of Jesus, does not constitute evidence either way on Jesus' infancy.  And it doesn't matter if the reference shows somebody thought Jesus was "born" there, Jason's purpose in the article is not to establish that Jesus was born in Nazareth, but that Jesus was virgin-born.  Nothing in Mark 1:24 supports any concept of virgin birth.

Other Christian scholars see nothing about Jesus infancy in this passage:

“The Holy One of God” (ὁ ἃγιος τοῦ Θεοῦ). The demon addresses Jesus as “Jesus, the Nazarene.” After asking about the purpose of Jesus’ coming, the spirit then demonstrates his knowledge of Jesus’ true identity, “The Holy One of God.”

Guelich, R. A. (2002). Vol. 34A: Word Biblical Commentary : Mark 1-8:26.
Word Biblical Commentary (Page 57). Dallas: Word, Incorporated.

 Engwer continues:

The theme of Davidic ancestry is present as well (10:47-48, 11:10, 12:35-37). Again, keep in mind the implication of a Bethlehem birthplace.

Even granting Jesus was born in Bethlehem, this does nothing to speak to his being born of a virgin.  Do you  believe Josephus when he says a cow gave birth to a lamb, merely because he correctly mentions Jerusalem and the Temple?  Probably not.

And a high estimate of Jesus' character, with its implications for Jesus' childhood, is present in Mark (1:24), as in the other gospels.

Correction, the story has a story character that gave a high estimate of Jesus.  Trying to establish the historicity of such high estimate by blindly buh-leeving the account is about as stupid as arguing that Donald Trump is a good politician because one of his enemies once said something good about him.

The belief of Jesus' own family that he was crazy, and their refusal to believe his miraculous claims, have more weight than Mark's hearsay quotation of a demon-possessed man:

 20 And He came home, and the crowd gathered again, to such an extent that they could not even eat a meal.
 21 When His own people heard of this, they went out to take custody of Him; for they were saying, "He has lost His senses." (Mk. 3:20-21 NAU)

 5 For not even His brothers were believing in Him. (Jn. 7:5 NAU)

 Inerrantist Brooks is quite explicit that "his own people" in Mark 3:21 means "family" and that they thought Jesus was acting like a crazy person to the point that they intended to take him by force:

3:21 In the Greek text the subject of the first two clauses is literally “those with him.” The KJV and RSV (1st ed.) interpret this to mean “his friends,” the NASB and NKJV “his own people,” and the RSV (2nd ed.), NRSV, NEB, REB, and NIV “his family.” In view of vv. 31–32 the last of these is certainly correct. The idea that Jesus’ family opposed him troubled some ancient copyists who changed the text to read, “When the scribes and the rest heard.” The concern of Jesus’ family was not likely limited to his physical needs (v. 20); they probably were more concerned about the family’s reputation because in their estimation Jesus was acting in a fanatical and even insane way. The same verb is used in Acts 26:24 and 2 Cor 5:13 and means literally to stand outside of oneself. The verb translated “to take charge” means to arrest in 6:17; 12:12; 14:1, etc. Evidently they intended to seize Jesus and force him to return to Nazareth with them.

Brooks, J. A. (2001, c1991). Vol. 23: Mark (electronic).

Engwer continues:

Jesus' mother, as in the infancy narratives, is named Mary (6:3).

I don't see how the infancy narratives getting the name of the mother right is supposed to lend any credence to their mythical elements.  There is nothing about getting somebody's name correct that suggests the author is intending to assert only historical facts.  1st John was written in part to combat a proto-gnosticism in which some heretics got the name of Jesus right, but got the theology wrong.  Thousands of Christian Jews got Paul's name correct, but apparently trusted in an allegedly false rumor about him, Acts 21:18-24.

Jesus has siblings (6:3), and Mark describes them in a way that corroborates the infancy narratives, as I explained when I discussed Matthew's gospel.

All that need prove is that the infancy narratives have expanded upon less mythical facts in the earlier Markan gospel.   And the fact that most scholars agree that Luke and Matthew are borrowing material from Mark anyway, means the "corroboration" is useless because it isn't independent.

The people of Nazareth in Mark 6:1-6 seem to be aware of some unusual circumstances surrounding Jesus' birth. Joel Marcus writes:
    In Jewish sources the father's name is normally used to identify the son even when the father is dead (see e.g. Do'eg son of Joseph in b. Yoma 38b and Jesus son of Jesus in the Babatha archive; cf. Ilan, "Man," 23 n. 3). Contrary to this custom, Jesus is designated [in Mark 6:3] by his mother's name rather than his father's. Both Matthew and Luke revert to the usual pattern, Luke 4:22 reading "the son of Joseph" (cf. John 6:42) and Matt 13:55 "the son of the carpenter."…

Sure is funny that when inerrantists can find some support for their theory in the Talmud, they reference the Talmud as if the support is beyond question.  But when others point to statements in the Talmud to the effect that, say, children as young as 3 are suitable for sexual relations, then suddenly, the inerrantists remind us of what an unreliable grab bag of contradictory convoluted traditions the Talmud is.

 Indeed, the relevant portion from the Talmud says the saying was uttered by a Rabbi "Rabina"

Rabina raised an objection: The story of Doeg b. Joseph whom his father left to his mother when he was a young child:

It was this same "Rabina" who asserted that Gentile girls become "suitable for sexual relations" at 3 years of age:

  Said Rabina, “Therefore a gentile girl who is three years and one day old, since she is then suitable to have sexual relations, also imparts uncleanness of the flux variety.”     From Abodah Zarah 36B-37A:

Will somebody trifle that Rabina was faithful to the historical truth about the Jewish custom of calling sons after their fathers even after the father died, but was conveniently not faith to the truth about Jewish customs in his pedophilia?

    Ilan ("Man") has shown that a matronymic could be used when the mother's pedigree was superior to the father's, but that can scarcely be the case here, since Davidic descent was the most important of all, and Jesus was a Davidide on his father's side…

Jesus was Davidic because of his mothers' side too according to most scholars:

The problem would have been insoluble had it not been for the wisdom of God. The solution lay in the genealogy of Mary, recorded in Luke 3 (vv. 23–38), which goes back through Nathan to David. Through Mary Jesus is physically an heir of David, and through Joseph He receives the legal right to the throne (while sidestepping the physical curse upon that line). “Oh, the depth of the riches both of the wisdom and knowledge of God! How unsearchable are His judgments and unfathomable His ways!” (Rom. 11:33). Because of His miraculous conception our Lord receives title to the throne of David in the Kingdom of God. Dying without a son (cf. Isa. 53:8), He carried that title to the right hand of God. It is most interesting to note that since the destruction of Jerusalem in ad 70 it has been impossible to reconstruct the Davidic genealogy. The only reliable genealogies we have are those in Matthew and Luke, and they point incontrovertibly to Jesus of Nazareth as the virgin’s son—the divinely promised King of the Jews.

"The Virginal Conception of Our Lord  in Matthew 1:18-25  —  David J. MacLeod*  

The Emmaus Journal. 1999 (electronic ed.). 

EMJ—V8 #1—Sum 99—30.  Garland, TX: Galaxie Software.

 That Luke records Mary's genealogy was a position taken by many in the early church.  See Mary Through the Centuries: Her Place in the History of Culture, by Jaroslav Pelikan.  Paul David Younan says the genealogy of Matthew traces Mary back to David.  So let's not get too cocky about how Joseph is so important to establishing that Jesus descended from David.

Calvin thought Luke was tracing Mary's ancestry back to David:

But we have not yet replied to their objection, that the ancestry of Joseph has nothing to do with Christ. The common and well-known reply is, that in the person of Joseph the genealogy of Mary also is included, because the law enjoined every man to marry from his own tribe. It is objected, on the other hand, that at almost no period had that law been observed: but the arguments on which that assertion rests are frivolous.

Calvin, J. (2000). Calvin's Commentaries (electronic ed.). 

electronic ed. (Mt 1:18). Garland, TX: Galaxie Software.

R.A. Torrey agreed:

1. The genealogy given in Matthew is the genealogy of Joseph, the reputed father of Jesus, his father in the eyes of the law. The genealogy given in Luke is the genealogy of Mary, the mother of Jesus, and is the human genealogy of Jesus Christ in actual fact.

Torrey, R. (1998, c1996). Difficulties in the Bible : Alleged errors and contradictions. 

Willow Grove: Woodlawn Electronic Publishing.

Tertullian, Against Marcion, Book 4:

Isaiah He says: “Hear me, and ye shall live; and I will make an everlasting covenant with you,” adding “the sure mercies of David,” in order that He might show that that covenant was to run its course in Christ. That He was of the family of David, according to the genealogy of Mary, He declared in a figurative way even by the rod which was to proceed out of the stem of Jesse.

Schaff, P. (2000). The Ante-Nicene Fathers (electronic ed.). Garland, TX: Galaxie Software.

  Engwer continues:

    These alternate theories being found wanting, and given the hostile nature of the confrontation, it is likely that the use of Jesus' mother's name is a slur against his legitimacy, as Stauffer ("Jeschu") and S. Wilson (Strangers, 188) among others argue. This aspersion would correspond to the tendency in later Jewish traditions to portray Jesus as a bastard (see e.g. Origen Against Celsus 1:28-32, 39, 69; b. Sanh. 67a), a pattern that may already be reflected in John 8:41. Ilan, though disagreeing with this exegesis, cites an interesting parallel, the derogatory designation of Titus as "the son of Vespasian's wife" in 'Abot R. Nat. 7 (B), which implies that he is illegitimate (see Ilan, "Man," 42-43 n. 86, and cf. Saldarini, Fathers, 68 n. 15). McArthur ("Son of Mary") argues against the implication of illegitimacy in Mark 6:3 that "son of Mary" is an informal reference, not a formal genealogical expression, and that there is nothing necessarily unusual or derogatory about an identification by the mother's name in such informal contexts (cf. e.g. 1 Kgs 17:17; Acts 16:1). But Mark 6:3 comes closer to being a genealogical formula than the parallels cited because of the extensive list of other male family members. McArthur's theory, moreover, does not explain the apparent embarrassment of Matthew and Luke at Mark's term

You don't know that it was embarrassment that led Matthew or Luke to read a bit different.  Matthew says:

 54 He came to His hometown and began teaching them in their synagogue, so that they were astonished, and said, "Where did this man get this wisdom and these miraculous powers?
 55 "Is not this the carpenter's son? Is not His mother called Mary, and His brothers, James and Joseph and Simon and Judas?
 56 "And His sisters, are they not all with us? Where then did this man get all these things?"
 57 And they took offense at Him. But Jesus said to them, "A prophet is not without honor except in his hometown and in his own household."
 58 And He did not do many miracles there because of their unbelief. (Matt. 13:54-58 NAU)

 If indeed it is true that Matthew is here showing "apparent embarrassment" over Mark's more terse "son of Mary reading, then we have to ask why Matthew felt embarrassed by this reading.  Did he think he discovered a slur in the crowd's quoted language that Peter's interpreter Mark had missed? 

Does that sound like Matthew thought Mark wrote inerrantly?  Indeed, why else do Matthew and Luke change Mark's wording, if they thought Mark's choice of wording was inerrant?

Why should the teller of the virgin birth story feel the last bit embarrassed by an earlier gospel author reporting that Jesus was merely "son of Mary"?  Did Matthew perceive that this was not a mere sign that the people perceived something peculiar about Jesus' birth, but that they had good reason to believe Jesus was an authentic naturalistic bastard fathered by somebody other Joseph?

Furthermore, Metzger holds that there are early and wide textual variants in which the crowd in Mark 6:3 does mention Jesus' father Joseph, so apparently even early scribes felt Mark's choice of wording would likely be taken as contrary to the similar statement in Matthew 13:35:

6.3 te,ktwn( o` ui`o,j {A}

All uncials, many minuscules, and important early versions read, “Is not this the carpenter, the son of Mary …?” Objection was very early felt to this description of Jesus as carpenter,11 and several witnesses (including p45) assimilate the text to Mt 13.55 and read, “Is not this the son of the carpenter, the son of Mary …?” The Palestinian Syriac achieves the same result by omitting o` te,ktwn.

 There is no reason why the emphasis on Jesus' mother throughout the gospels cannot simply imply that Joseph was dead by the time Jesus began his ministry.  Engwer is crazy to try to squeeze so much out of one phrase in Mark 6:3

Engwer continues his rebuttal to MacArthur:

or reckon with the hostile context of our passage

Maybe he doesn't, but there is hostile context in Matthew 13:55 too.

In my post on Matthew's gospel, I mentioned that we should take note of how themes in the infancy narratives are connected to other concepts.

Yeah, like themes in Greek mythology are connected to other concepts.  Big deal. But thanks for making clear that you aren't talking to skeptics.  You are clearly addressing only those who already believe and therefore need far less argument to cross the line and assert the historicity of Jesus' virgin birth.

If an early Christian source applies passages like Isaiah 11 and 52-53 to Jesus, how likely is it that he didn't also think Jesus fulfilled a Christmas passage like Isaiah 9?

Isaiah 9 was allegedly a prediction of Christ's ministry to the Gentiles.  If the gospels are historically reliable when they assert Jesus had a significant ministry to Gentiles:

  45 But he went out and began to proclaim it freely and to spread the news around, to such an extent that Jesus could no longer publicly enter a city, but stayed out in unpopulated areas; and they were coming to Him from everywhere. (Mk. 1:45 NAU)

12 Now when Jesus heard that John had been taken into custody, He withdrew into Galilee;
 13 and leaving Nazareth, He came and settled in Capernaum, which is by the sea, in the region of Zebulun and Naphtali.
 14 This was to fulfill what was spoken through Isaiah the prophet:
 15 "THE LAND OF ZEBULUN AND THE LAND OF NAPHTALI, BY THE WAY OF THE SEA, BEYOND THE JORDAN, GALILEE OF THE GENTILES--
 16 "THE PEOPLE WHO WERE SITTING IN DARKNESS SAW A GREAT LIGHT, AND THOSE WHO WERE SITTING IN THE LAND AND SHADOW OF DEATH, UPON THEM A LIGHT DAWNED."
 17 From that time Jesus began to preach and say, "Repent, for the kingdom of heaven is at hand." (Matt. 4:12-17 NAU)

 15 But Jesus, aware of this, withdrew from there. Many followed Him, and He healed them all,
 16 and warned them not to tell who He was.
 17 This was to fulfill what was spoken through Isaiah the prophet:
 18 "BEHOLD, MY SERVANT WHOM I HAVE CHOSEN; MY BELOVED IN WHOM MY SOUL is WELL-PLEASED; I WILL PUT MY SPIRIT UPON HIM, AND HE SHALL PROCLAIM JUSTICE TO THE GENTILES.
 19 "HE WILL NOT QUARREL, NOR CRY OUT; NOR WILL ANYONE HEAR HIS VOICE IN THE STREETS.
 20 "A BATTERED REED HE WILL NOT BREAK OFF, AND A SMOLDERING WICK HE WILL NOT PUT OUT, UNTIL HE LEADS JUSTICE TO VICTORY.
 21 "AND IN HIS NAME THE GENTILES WILL HOPE."
 (Matt. 12:15-21 NAU)

...and if the apostles really heard the resurrected Jesus commission THEM to preach to Gentiles (Great Commission, Matthew 28:19), then what are the odds that Peter and the church would, shortly after Jesus ascended, regard the salvation of Gentiles as some shocking unexpected theological development they'd never have guessed without a special divine revelation to Peter, as they do in Acts 11:18?

Or does Engwer think such questions as his beg too many presuppositions to be answered?  If Engwer can safely assume the first-century Christian knows doctrine B because he knows doctrine A, why can't skeptics similarly argue that Acts 10-11 is false history, on the ground that Peter surely knew doctrine B (Gentiles could be saved) because he knew doctrine A (Jesus taught Gentile salvation)?

Mark often refers to the theme of Messianic prophecy fulfillment, even opening his gospel with it (1:2-3). Since Isaiah 9 and Micah 5 are two of the most explicitly Messianic passages in the Old Testament, how likely is it that Mark didn't think Jesus fulfilled those passages?

About as likely as Matthew thinking Mark's language was inaccurate.  Compare "could" do no miracle (Mark 6:5) with Matthew's theologically easier "did not" do any miracle there (13:58).

You apologists think Daniel 9 is an exceptionally powerful apologetic since it allegedly shows somebody in 600 b.c. predicting something about Jesus with amazing precision, but despite NT authors liking the idea of the OT predicting Jesus, nobody in the NT makes anywhere near the big deal out of it that you do.

One of the problems with critics of the infancy narratives is that they're too focused on what a source like Mark explicitly tells us.

That's because you enter dangerous territory when you try to draw conclusions from an author's alleged inferences or silence.  Mark's failure to explicitly mention the virgin birth, however, is so significantly unexpected that it screams out for an explanation other than his alleged acceptance of it.

Much of the relevant evidence is of an implicit nature.

Which might explain why your arguments are shockingly unpersuasive to any except inerrantist fundamentalists.

Mark doesn't say much directly about Jesus' childhood.

Probably because he didn't think anything about Jesus' childhood had significant relevance to the gospel message.  Again, Jesus replies in opposition to the women who brings up the subject of his mother, Luke 11, supra.

His gospel is derived from what Peter taught, and Peter's apostolic work was focused on what occurred from the ministry of John the Baptist onward (Acts 1:21-22).

Which is precisely why there's no need to assume Peter believed anything about the virgin birth story.

Peter would typically begin his public teaching with John and Jesus in their adulthood,

No, Peter's sermon in Acts 2:14 ff neither expresses nor implies anything about John the Baptist.  You are asserting patterns merely because, by your own admission, you detected Peter doing something in a single bible passage.  Peter's doing something once does not establish a pattern.

so Mark started his gospel there. But there are some implications for Jesus' childhood in what Mark tells us, even though he wasn't focused on the subject.

And what you overlook is that if Mark himself believed what you think he did (i.e., Jesus was born of a virgin, this is why there was a scandal about Jesus father or childhood), then Mark's failure to explicitly assert something in favor of the virgin birth is a screaming silence that suggests the assumption is wrong, and it is for another reason that he fails to explicitly assert any virgin birth matter.

Something else should be said here about the gospels and other early sources in general. Once Jesus begins publicly teaching and performing so many miracles, his adulthood overshadows his childhood.

No it doesn't, there was a lady who directed his attention to the blessedness of his mother, giving him the perfect opportunity to explicitly assert something about how his mother possessed any type of special uniqueness, yet Jesus opposes this female speaker and directs her away from the subject of his mother.  Luke 11:27-28, supra.

When Jesus was standing before people, teaching them and performing such a large number and variety of miracles in their midst, why would he spend much time pointing them to a far smaller number of miracles that occurred a few decades earlier, when he was a child?

Maybe for the same reason Matthew and Luke did when they did their preaching on the virgin birth?

Why would the New Testament authors and others involved give much attention to his childhood?

Ask Matthew and Luke, they can explain how it is that something in Jesus' childhood retained its historical importance despite Jesus himself becoming the center of attention.

Just as Old Testament prophecies about the Messiah's childhood are far outnumbered by predictions about his adulthood,

Yup, you aren't talking to skeptics.  There are no OT prophecies about Jesus' childhood, unless you are talking in the useless-for-apologetics sense of typology.

it makes sense for matters pertaining to Jesus' childhood to only occasionally come up during his adult ministry.

On the contrary, it makes sense to assert that the virgin birth stories of Jesus are late inventions, and we normally expect the earlier account to be less encumbered with embellishments, which appears to be exactly what happened here.