The following is an excerpt from The MacArthur New Testament Commentary on Matthew 2 .

Now all this took place that what was spoken by the Lord through the prophet might be fulfilled, saying, “Behold, the virgin shall be with child, and shall bear a Son, and they shall call His name Immanuel,” which translated means, “God with us.” (Matthew 1:22–23)

At this point Matthew explains that Jesus’ virgin birth was predicted by God in the Old Testament. The Lord clearly identifies the birth of Christ as a fulfillment of prophecy. All this refers to the facts about the divine birth of Jesus Christ. And the great miracle of His birth was the fulfillment of what was spoken by the Lord through the prophet. That phrase gives a simple, straightforward definition of biblical inspiration as the Word of the Lord coming through human instruments. God does the saying; the human instrument is only a means to bring the divine Word to men. Based on these words of the Lord given through Matthew, the Old Testament text of Isaiah must be interpreted as predicting the virgin birth of Jesus Christ.

Matthew repeatedly uses the phrase might be fulfilled (2:15, 17, 23; 8:17; 12:17; 13:35; 21:4; 26:54; etc.) to indicate ways in which Jesus, and events related to His earthly ministry, were fulfillments of Old Testament prophecy. The basic truths and happenings of the New Testament were culminations, completions, or fulfillments of revelation God had already made-though often the revelation had been in veiled and partial form.

The scene in Isaiah 7 is the reign of King Ahaz in Judah. Though son of the great Uzziah, he was a wicked king. He filled Jerusalem with idols, reinstated the worship of Molech, and burned his own son as a sacrifice to that god. Rezin, king of Syria (Aram), and Pekah, king of Israel (also called Samaria at that time), decided to remove Ahaz and replace him with a king who would do their bidding. In the face of such a threat to the people of Israel and to the royal line of David, Ahaz, instead of turning to God for help, sought the help of Tiglath-pileser, the evil king of the Assyrians. He even plundered and sent to Tiglath-pileser the gold and silver from the Temple.

Isaiah came to Ahaz and reported that God would deliver the people from the two enemy kings. When Ahaz refused to listen, Isaiah responded with the remarkable messianic prophecy of 7:14.

How did a prediction of the virgin birth of Messiah fit that ancient scene? Isaiah was telling the wicked king that no one would destroy the people of God or the royal line of David. When the prophet said, “The Lord shall give you a sign,” he used a plural you, indicating that Isaiah was also speaking to the entire nation, telling them that God would not allow Rezin and Pekah, or anyone else, to destroy them and the line of David (cf. Gen. 49:10; 2 Sam. 7:13). Even though the people came into the hands of Tiglath-pileser, who destroyed the northern kingdom and overran Judah on four occasions, God preserved them just as He promised.

Isaiah also refers to another child who would be born; and before that child (Maher-shalal-hash-baz) would be old enough to “eat curds and honey” or “know enough to refuse evil and choose good,” the lands of Rezin and Pekah would be forsaken (7:15–16). Sure enough, before the child born to Isaiah’s wife was three years old those two kings were dead. Just as that ancient prophecy of a child came to pass, so did the prophecy of the virgin birth of the Lord Jesus Christ. Both were signs that God would not ultimately forsake His people. The greatest sign was that Immanuel, which translated means, “God with us,” would come.