What does Isaiah 7:9 mean?
The beginning of this verse seems to finish the prophecy revealed at the end of the previous statement (Isaiah 7:8). Within 65 years, Ephraim, the northern ten tribes of Israel, will be shattered from being a people.This verse then follows the poetic form of Isaiah 7:8 by calling the capitol and the king of Ephraim "the head." The Lord seems to be saying to Ahaz not to be afraid because the entire nation of Ephraim will cease to exist in 65 years. Isaiah concludes this message from the Lord with a powerful message that if Ahaz is not firm in his faith, he has no foundation at all.
This raises several questions for readers and likely for Ahaz. How does the fact that Ephraim will be wiped off the map in 65 years help him with the imminent siege of Jerusalem? Doesn't he have to deal with that problem right away? The Lord does not answer that question and instead tells the king to trust Him (Isaiah 7:4).
Although it is not described in this passage, the Lord is telling Ahaz to trust him instead of trusting someone else. Ahaz already has or will soon turn to the king of Assyria, Tiglath-pileser, for help with these and other enemies of Judah (2 Chronicles 28:16). The results of this decision will be even more disastrous. The Lord is telling Ahaz to be firm and fearless in trusting Him, instead of panicking and hoping for help from Assyria.