Matthew’s account passes over in silence about how and when Joseph found out that Mary was pregnant through the operation of holy spirit. An engagement required a woman to remain chaste, and unfaithfulness to her future husband constituted adultery. Moreover, the engagement was just as binding as marriage and could only be terminated by giving the woman a divorce certificate that would allow her to marry another man. Therefore, Joseph faced a serious dilemma on account of Mary’s pregnancy prior to their being united in marriage. To all appearances, she had been unfaithful, and the truthful explanation Mary may have given him could not be verified. While miracles had occurred in the past, nothing of this nature had ever taken place. (Matthew 1:18)
Being righteous or a man who wanted to do what is right, Joseph did not want to expose Mary to public shame. So he considered divorcing her secretly, perhaps in the presence of two witnesses. Then, in a dream, an angel appeared to him and said, “Joseph, son of David, do not fear to take Mary as your wife, for what is conceived in her is through holy spirit. And she will give birth to a son, and you shall call his name Jesus, for he will save his people from their sins.” (Matthew 1:19-21)
Upon awakening from his dream, Joseph followed through on the angelic direction and took Mary as his wife but had no intimate relations with her until she gave birth to the son whom he called Jesus. (Matthew 1:24, 25)
Mary’s pregnancy fulfilled the words of the prophet Isaiah (7:14), “Behold! The virgin will conceive and will give birth to a son, and they will call his name ‘Immanuel,’ which means, ‘With us [is] God.’” (Matthew 1:22, 23; see the Notes section for a detailed consideration of Isaiah’s prophecy and its relation to the foretold Messiah.)
The name “Jesus” means “YHWH is salvation” and so pointed to his role as God’s means for salvation or deliverance from sin. As the angel explained, this is the name the child should be given because he would “save his people from their sins.”
With the exception of different forms of the verb for “call,” the wording of Isaiah 7:14 in extant Septuagint manuscripts is the same as in Matthew 1:23. The Masoretic Text refers to the woman who would give birth as ‘almáh (a young woman who may be either a wife or a virgin). In the Septuagint and in Matthew 1:23, the corresponding term is parthénos, (“virgin”). By reason of her engagement, Mary already belonged to Joseph as his “young woman” and was also a virgin. The more specific Greek term reflected the precise circumstances that uniquely applied in Mary’s case. Knowing Jesus to be the Son of God whose life as a human came about through the direct operation of holy spirit and not the usual process of procreation, Matthew recognized that the words of Isaiah 7:14 matched exactly what had occurred in Jesus’ case and could therefore refer to them as having been fulfilled.
Isaiah’s prophecy does, however, also relate to the situation existing in his time. The Syrian king Rezin formed an alliance with Israelite king Pekah. Both were intent on overthrowing King Ahaz, replacing him with the son of Tabeel. Upon coming to know about this conspiracy, Ahaz and his subjects gave way to fear. YHWH directed Isaiah to take his son Shear-jashub to meet Ahaz. The message for the king was that he should not lose courage, for the attempt to dethrone him would fail. (Isaiah 7:1-9)
Ahaz was invited to ask for a confirmatory sign, but the faithless king refused to do so. Nevertheless, through Isaiah, YHWH did announce a sign: “The maiden [is] pregnant and is bearing a son, and she will call his name Immanuel.” Before this boy would be able to discriminate between good and bad, the threat from the kingdoms of Israel and Syria would have ceased to exist, and he would be eating curds and honey. The kingdom of Judah, however, would be subjected to Assyrian aggression. (Isaiah 7:10-17)
Historically, the conquest of Assyrian monarch Tiglath-pileser III brought an end to the threat of the ten-tribe kingdom of Israel and the kingdom of Syria. The Syrian capital Damascus fell to the Assyrian forces, and King Rezin was killed. The Assyrians invaded the Israelite territories of Gilead, Galilee, and Naphtali, taking many of the inhabitants into exile. The kingdom of Judah also suffered from Assyrian invasion. (2 Kings 15:29; 16:9; 1 Chronicles 5:6, 26; 2 Chronicles 28:20) This may explain why the boy Immanuel is spoken of as eating curds and honey. Assyrian campaigns disrupted the usual agricultural operations, forcing many in the kingdom of Judah to subsist largely on wild honey and dairy products. (Isaiah 7:20-25)
The identity of the maiden and her child in the time of Isaiah is unknown, and this aspect more readily served the purpose of pointing forward to the birth of the promised Messiah, Jesus. As the direct representative of his Father, Jesus lived up to the name “Immanuel,” meaning “with us [is] God.” In the person of his unique Son, God was indeed with his people.