Isaiah 62:6-12 is the first reading assigned for Christmas Day.
Like the Isaiah 9:2-7 reading assigned for Christmas Eve, the commentaries, appropriately, see little connection between this particular proclamation of salvation and the birth of Jesus. Rather, our passage concerns Zion, the name of the hill upon which the city of Jerusalem is located, and anticipates the ultimate restoration of the city which will be called "The Holy People," "The Redeemed of the LORD," "Sought Out," and "A City Not Forsaken." How such an "Old Testament" text speaks to us on Christmas Day, however, will emerge from a consideration of the wider context.
The book of Isaiah consists of three sections that contain oracles from three prophets addressing different historical periods and concerns yet connected in their belief in the future exaltation of Zion, of which our text is a prime example.
There have been several attempts to discern a "chiastic" structuring of the major part of "Third Isaiah" in the final form of the book. They tend to be excessively complex and have been properly criticized (usually by others who then proceed to offer their own literary architectures!). There are, however, basic themes that do seem to fall into a concentric pattern:
A 56:1-8 Foreign worshipers
B 56:9-59:15a Ethical righteousness
C 59:15b-21 Divine Warrior
D 60--62 Eschatological hope
C' 63:1-6 Divine Warrior
B' 63:7-66:17 Ethical righteousness
A' 66:18-24 Foreign worshipers
As can be seen, chapters 60-62 appear at the center of Third Isaiah. They portray Jerusalem as a bereaved woman who will be restored as a home for the righteous exiles returned to their homeland and to communion with their God. Scholars are generally agreed that these three chapters, bound together by the theme of the restoration of Zion, each present a lament with a corresponding response. The laments arise out of the people's despair at the deplorable conditions in Jerusalem upon their return and the tardiness of God's fulfillment of the glorious promises made in Second Isaiah.
Thus, an anonymous prophet (Third Isaiah?) resolves to pray unceasingly for Zion until the city is fully vindicated and exalted in the eyes of the Gentiles (vv. 1-2a). As an indication of this new status, God will give the city, lovingly held as a diadem, a new name (v. 2b-3). Once called "Forsaken" (or "Abandoned") and "Desolate," Jerusalem will now be called "My Delight is in Her" and "Married" (v. 4). Second Isaiah had assured Israel that God had not divorced her (Isaiah 50:1-3), though there was abandonment of Israel by her husband, Yahweh (see Isaiah 49:14; 54:6-7; 60:15, all azab, as here) −a "trial separation" as it were! But now Yahweh ("your builder," see Psalm 147:2; and the similar, "For your Maker is your husband" Isaiah 54:5) will (re)marry Jerusalem (vv. 4-5).
Furthermore, in our assigned text, the prophet has posted sentinels on the city walls who will also pray unceasingly for Zion (v. 6). Their task is to pester God "all day and all night." They are to "give him (God) no rest" until the restoration of the city is complete (v. 7)! This audacious claim is based upon God's promise, which is repeated (for God's benefit?) in verses 8-9.
Curiously, an unidentified group (though possibly "the end[s] of the earth") is urged to prepare the way for the return of God's people in language reminiscent of Isaiah 40:3-5, 10, yet another indication of the prophet's confidence in the ultimate fulfillment of the divine promise (v. 10).
"See, your salvation comes," verse 11 proclaims. Indeed, the Septuagint (LXX), Syriac, Vulgate, and Targum all read "Savior" (soter) for "salvation." Whether "salvation" or "savior" is correct, for Christians celebrating the birth of Jesus Christ this day, there can be only one reading of Isaiah's message. While the prophet was the first to catch a glimpse of a resplendently restored Zion in verses 1-5, joined by the sentinels in verses 6-7; following Yahweh's sworn promise to the present inhabitants of Jerusalem in verses 8-9, it is "the end(s) of the earth" who are finally to announce to Zion the coming of deliverance (v. 11). In this way, Third Isaiah has transformed Second Isaiah's message of the impending return of the exiles from Babylon into a message of the utter restoration of Jerusalem at the end of time by applying it to a new situation. In the same way, we, too, are charged with announcing the arrival of God's eschatological salvation in Jesus, the Christ, on this the celebration of his birth.
1John N. Oswalt, The Book of Isaiah Chapters 40-66 (Grand Rapids: Eerdmans, 1998).