THE THRUST OF ISAIAH 10:5-34 is clear enough. At the beginning and the end (Isa. 10:5-19, 28-34), the emphasis is on the fact that mighty Assyria will herself be crushed after God has used her to punish his own covenant people. In the central section (Isa. 10:20-27), the people of God are encouraged neither to fear nor to rely on Assyria, but to rely on the Lord alone.
I shall begin with this central section (Isa. 10:20-27). One of its great themes is "the remnant." Judgment will fall, but the people of God wilzl not be wiped out: there will be a remnant. This "remnant of Israel" (Isa. 10:20) probably does not refer to the remnant from the northern kingdom of Israel, but to the remnant of Israelites from the south as well as the north (note the parallel "house of Jacob," the common ancestor, and "remnant of Jacob," Isa. 10:20, 21). "Destruction has been decreed, overwhelming and righteous" (Isa. 10:22), against "the whole land" (Isa. 10:23). But a remnant will return, not just to a place, but "to the Mighty God" (Isa. 10:21). In the light of such promises, the people of the southern kingdom, God's "people who live in Zion" (Isa. 10:24), should not be afraid of the Assyrians, even though they are beaten by them. God's wrath against Israel will end; indeed, it will in short order turn against the Assyrians themselves (Isa. 10:25-27).
That brings us to the sections on either side of Isaiah 10:20-27. At one level the theme is plain enough. The God who uses Assyria to punish his wayward covenant community nevertheless holds Assyria responsible for her own sins, and will ultimately destroy them. The empire that is nothing more than a battle ax in the hand of God, wielded against a rebellious nation (Isa. 10:15), will itself ultimately be axed down by God (Isa. 10:34). The pronouncement of this judgment is designed to foster faith and perseverance on the part of the remnant.
There is an important subsidiary theological theme in this chapter; the biblical tension between God's sovereignty and human responsibility surfaces in powerful ways. God uses mighty Assyria as if it were nothing but a tool in his hands (Isa. 10:5, 15). He himself dispatches Assyria to punish Israel (Isa. 10:6). Assyria, of course, is totally unaware of God's control. Nevertheless, she is held responsible for her own actions and attitudes, not least her arrogance and pride (Isa. 10:7-11, 13-14). So God will punish her (Isa. 10:12). This tension between God's sovereignty and human responsibility is not to be despised or rejected, but seized with gratitude, for it will preserve us both from denying the reality of evil and from imagining that evil could ultimately triumph. Meditate on Acts 2:23; 4:27-28.