Has any other passage in Matthew’s Nativity narratives raised so many questions? But what was Matthew really trying to do in 1:18-25?
Raymond E. Brown gives a succinct answer: He was proclaiming that Jesus is God’s Son and the promised Messiah of David’s line, begotten not by Joseph but by the Holy Spirit.
Geza Vermes adds that whatever else the words of the passage may say, “they certainly describe a child conceived in a way different from the normal and convey that the person to be born will be very specially connected with God.”
In the lst century Jewish tradition marriage was a two step process as vs. 18 reveals: 1) Betrothal, when at 12-13, a young woman became her husband’s wife, but still lived in her parents’ home. Any infringement of this relationship was considered adultery. 2) After a community ceremony, the couple lived together in the husband’s home.
Sexual customs varied in different places. In Judea, some sexual relations were not frowned on. In Galilee, premarital relationships were more strict. Matthew’s tone reflected the Galilean culture, but the subsequent birth states that they lived in Bethlehem, in Judea.
The role of the Holy Spirit was not to be the male element in a sexual act, but the divine agent in an unusual conception. The lead actor in Matthew’s narrative was Joseph. With the greatest of kindness he was unwilling to enforce his right of charging Mary with adultery. According to the law, the penalty was death by stoning. (Deuteronomy 22:20-21). He learned of God’s plan from an angel in a dream (vs. 20). This shifted his attitude to a more merciful compromise which did not detract from his upright character. Mary’s conception “by the Holy Spirit” was a matter of reverence and awe rather than strict legalism.
Dreams and angels have a significant place in scripture as the means by which God’s will and purpose are revealed. Joseph is to become the legal if not the natural father of God’s Son. The child is to be named Jesus, the Greek translation of the Hebrew phrase for “YHWH saves.” (Pronounced with vowels as “Yahweh.”)
Matthew then quoted, mistakenly as we now know, from Isaiah 7:14. Originally, that referred to a child to be born to King Ahaz of Judea (735-715 BCE). In the 8th century BCE that was a time of considerable religious and political chaos, not unlike the 1st century CE. Matthew’s intent was purely Christological. His reference to this passage showed that as the birth of Davidic Messiah and son of God was not a miracle but a fulfillment of God’s plan made known in prophecy as then interpreted.
Accordingly to Brown, the divinely arranged conception supported rather than destroyed the concept of human genealogical descent. Matthew‘s explanation also gave Jews and Gentiles in Matthew’s audience an irrefutable argument against Jewish accusations late in the 1st century CE that Jesus was a mamzer, illegimate.