When Matthew applies to the conception of Jesus by the Holy Spirit the words of Isaiah that “the virgin shall conceive and bear a son, and they shall call his name Immanuel”, he is not saying that Jesus is God incarnate. The meaning of the allusion derives from the story that is being told in Isaiah 7-8. Matthew’s point, I think, is that the manner of Jesus’ conception is a sign to Israel at a time of crisis that God is with his people both to judge and to preserve.
John Doyle, however, asks about the relation of the boy Immanuel to the boy described in Isaiah 9:6-17—a passage very familiar to us from Christmas readings but, oddly, nowhere cited in the New Testament:
For to us a child is born, to us a son is given; and the government shall be upon his shoulder, and his name shall be called Wonderful Counselor, Mighty God, Everlasting Father, Prince of Peace. Of the increase of his government and of peace there will be no end, on the throne of David and over his kingdom, to establish it and to uphold it with justice and with righteousness from this time forth and forevermore. The zeal of the LORD of hosts will do this.
If the boy “Immanuel” is also the boy “Wonderful Counselor, Mighty God, Everlasting Father, Prince of Peace”, then there is surely a stronger case to be made for the incarnational reading of Matthew 1:23. However, I think it very unlikely that either Isaiah or Matthew thought that this was the case.
Three sons are mentioned in Isaiah 7-8. The name of each carries prophetic significance.
When the kings of Syria and Israel first come to wage war against Jerusalem, Isaiah takes his son Shear-jashub (“a remnant shall return”) to meet Ahaz and reassures him that the Lord will not allow the city to be harmed (7:1-9). Later a “prophetess”—Isaiah’s wife—bears him a son who is given the name Maher-shalal-hash-baz (“Speed spoil, hasten plunder!”), for “before the boy knows how to cry ‘My father’ or ‘My mother,’ the wealth of Damascus and the spoil of Samaria will be carried away before the king of Assyria” (Is. 8:3-44).
Similarly, the birth of the boy Immanuel (“God with us”) will be a sign to the doubting Ahaz, in the first place, that the “land whose two kings you dread will be deserted” (Is. 7:16), but more generally that God will be with his people when the crisis comes. The Lord will bring the Assyrian army against Judah because of the people’s rebelliousness, and it will fill the land (8:8). The invasion, however, will come to nothing because ultimately God is with his people (Is. 8:10).
The question of the relation of the boy Immanuel to Isaiah is difficult to answer. The mother is an unmarried woman. An unmarried woman would normally be a virgin, but that is a connotation of the word ‘almâ rather than its meaning. (Brian LePort has drawn attention to Mark Goodacre’s podcast asking “Is the Virgin Birth based on a Mistranslation?”) She is presumably known to king Ahaz, and it is sometimes suggested that she is a princess in his court, possibly Abia, the mother of Hezekiah (2 Kgs. 18:2). But if the chronology is to be trusted, Hezekiah would have been born around 740 B.C., five years before Ahaz began his coregency with his father. Besides, nothing in Isaiah 7:14-16 suggests that the boy was of royal descent, and there is no succession issue that needs to be resolved.
Nor can we say with any great confidence that Immanuel was Isaiah’s son. It is not stated explicitly as it is with the two other boys. Some would argue that Immanuel and Maher-shalal-hash-baz are the same boy since they fulfil the same prophetic function: before they reach a certain young age, Judah will be rescued from its enemies. But it seems unlikely that the unmarried woman of 7:14 is the same woman who bore him the other boys. Does Isaiah, then, father a child by another woman? It would be reasonable to suppose that the reference to the “sign” children given to Isaiah (Is. 8:18) included all three boys mentioned in the preceding narration, particularly since the birth of Immanuel is expressly said to be a “sign”. Perhaps, then, it would be more plausible to suggest that the mother of Immanuel was, like the “prophetess” of 8:3, one of the group of Isaiah’s disciples. I think I’ll go with that interpretation for now.
Isaiah commits this “testimony” and “teaching” to his disciples, and then waits to see what the Lord will do. He and his children are “signs and portents in Israel from the Lord of hosts” (Is. 8:16-18). If the people do not listen to this prophetic word but instead insist on consulting mediums and necromancers, “they will pass through the land, greatly distressed and hungry”; “they will be thrust into thick darkness” (Is. 8:19-22).
Now to consider the relationship of the boy Immanuel to the Davidic ruler whose birth is spoken of in Isaiah 9:6-7….
The argument so far has suggested that there is no basis for identifying Immanuel with this Davidic king. Motyer argues that the reference to “your land, O Immanuel” in Isaiah 8:8 implies that Immanuel is a king, but that is not a necessary reading.1 This word of the Lord is addressed to Isaiah, not to Immanuel, and the Hebrew name here may only mean “God is with us”, as in the Septuagint, where it is said that the camp of the king of Assyria “will be such as to fill the breadth of your country. God is with us.” Watts even includes it with the exclamation of verses 9-10.2
The boy of chapter 9 is given his own remarkable name: Wonderful-Counselor-Mighty-God-Everlasting-Father-Prince-of-Peace. Arguably this is also prophetically significant rather than a simple identification of the king with God: the Davidic king is a sign of God’s reign over his people. But, in any case, it differentiates him from the boy God-with-us. In the Septuagint the king is called only Messenger-of-Great-Counsel and is differentiated from the God who establishes his reign.
The two boys, moreover, serve quite different purposes. Immanuel is a sign to Judah and Jerusalem that the southern kingdom will soon be pitched into the gloom of a dire political crisis (cf. 8:22). The son of Isaiah 9:6-7, by contrast, will bring peace to the northern kingdom, lifting the gloom in which the people have long walked (9:1-5).
We also have to reckon with the fact that Matthew does not connect the child Immanuel with the Davidic king whose birth is described in Isaiah 9:6-7. He will later cite Isaiah 9:1-2 to account for the fact that Jesus began his ministry in Capernaum, in the territory of Zebulun and and Naphtali (Matt. 4:12-16), but he does not make the connection with the child of Isaiah 9:6-7. Nor does anyone else in the New Testament (well, perhaps Lk. 2:11).
So, in conclusion, Isaiah does not identify the boy Immanuel with the Davidic king of 9:6-7, and Matthew makes no reference to the latter passage. This leaves me where I started. Jesus’ conception is a fulfilment of Isaiah 7:14 because it too is a sign that God is with his people both to judge and to save.
Coincidentally, I have just this minute opened Craig Evans’ new commentary, Matthew (New Cambridge Bible Commentary) , and I find that he makes more or less my point:
Isaiah’s prophecy was not intended to be fulfilled seven centuries later; it was to be, and was, fulfilled in the lifetime of the feckless King Ahaz. The birth of the child who was named Immanuel took place long ago and had nothing to do with an awaited Messiah (and we in fact do not know who the young woman was—a new bride for Isaiah, or for Ahaz?—and we do not know who the young son was). But the event, which was indeed prophetic and is recorded in Scripture, took on typological significance for later generations. In the birth of Jesus, Matthew sees biblical history repeating itself, which is what typology is all about—the conviction that God will act in the future the way he acted in the past. If the birth of an infant, foretold with respect to a young woman, a virgin not yet wed, was a sign that God was with his people, to save and deliver, then how else was the surprising pregnancy of Mary to be understood? (47)