But was the gift of an infant boy, born to a young (virgin) woman, any way to win a war? Not for Ahaz, who sought the support of Tiglath-pileser, king of Assyria, and his army to rescue Judah (2 Kings 16:7–8). Judah’s king had turned to an earthly shield of defense, rather than turning to the strong tower of God’s heavenly name. Thus, the divine sign of the virgin birth stood against Ahaz’s attempt to “fight fire with fire.” The Lord and His kingdom would triumph in a way that was diametrically opposed to the way of the flesh: an instrument of inherent and apparent weakness (a virgin and child) would overcome those who had conspired to overthrow God’s reign. As John testifies in Revelation 12, the child and the woman prove from the heavenly perspective to be stronger than the dragon, Satan. This can only be true when God Himself is engaged in the battle.
The hostility between the heirs of God’s promise and His enemies goes back to the declaration of war in Genesis 3:15: “I will put enmity between . . . your offspring and her offspring.” In Isaiah 7, we see a further disclosure of how the woman’s seed would defeat the serpent’s—“not by might, nor by power, but by my Spirit, says the Lord of hosts” (Zech. 4:6). The virginal conception of Christ is one of many extraordinary examples of how God works out His powerful purposes through His weak chosen vessels, so that the glory will belong to Him and no other. Mary’s exultant song reaffirms that God’s saving providence topples the world’s hubris and hierarchy: “He has shown strength with his arm; he has scattered the proud in the thoughts of their hearts; he has brought down the mighty from their thrones and exalted those of humble estate” (Luke 1:51–52). The sign provided by God through Isaiah points to the singularity of divine wisdom in working contrary to the pattern of our natural expectations.
Son of David
Second, we see the importance of the setting when we read that the promise of the sign came to Ahaz as a member of the royal dynasty of David. The prophet’s rebuke included Ahaz, but it also extended beyond him: “Hear then, O house of David! Is it too little for you to weary men, that you weary my God also? . . . Behold, the virgin shall conceive” (Isa. 7:13–14). The sign of the virgin birth was indeed a seal of security in light of Judah’s approaching foes. But it was also an antidote to the corruption of David’s royal dynasty. This prophecy addressed the internal and spiritual barrenness of the “root of Jesse” as traced through the descendants of David.
Ahaz, as a “son of David,” together with his predecessors and progeny, represented one great apostasy that contributed to the covenant nation’s exile (cf. Dan. 9:8). God’s judgment extended from the head (crown) to the feet (citizens) of society, beginning with the unfaithful kings who had failed to rule in righteousness. Therefore, during their captivity in Babylon the Davidic throne lay vacant, as “there remains in it no strong stem, no scepter for ruling” (Ezek. 19:14).
During the exile, the results of royal infidelity and the nation’s rebellion were painfully acute, for the covenant people were ruled by a foreign king in a foreign land. This provokes the question, Does Israel’s faithlessness nullify God’s faithfulness? In short, will God’s kingdom perish because of the disobedience of the sons of David? Certainly not, for the Lord’s covenant with David is sure: “I will raise up your offspring after you, who shall come from your body, and I will establish his kingdom” (2 Sam. 7:12). God’s promise to bring David’s son (and Lord!) to His people would not fail, because He would create fruit by the Spirit, even when the flesh could not. The rebellious sons of David had grown spiritually barren, unable to produce a faithful heir. The Lord had to be the one to bring life from the dead, and so he sent His Son into the world: this too belongs to the significance of Isaiah’s sign. So while Jesus would be numbered in the generations of David (Matt. 1:1–17), the household of David would not generate the final royal heir: this work belonged to the Lord alone.
Only a little while later, Isaiah expanded on the character of this promised Son when he wrote: For to us a child is born, to us a son is given; . . . 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 (Isa. 9:6–7, emphasis added).
The sign that confronted Ahaz would at the same time bring comfort to God’s waiting people, for the word that lays low the flesh also lifts up those who embrace it in faith. Indeed, Christ’s incarnation in the womb of the Virgin Mary is part of the scandal and the wonder of the gospel: “This is the Lord’s doing; it is marvelous in our eyes” (Ps. 118:23).