What does Isaiah 9:9 mean?

The prophet Isaiah is describing the impending judgment looming over the peoples of Israel. These are the ten tribes of Jacob in the north. Isaiah is almost exclusively a prophet to the kings and the people of Judah: two tribes of Jacob in the south. He sometimes speaks of Israel, though. This is to hold them up as an example of what the Lord expects of His people and what He will do when they reject Him (Isaiah 9:8).

He insists that all the people will know that the Lord has brought destruction upon Israel. He uses the phrase "Ephraim and the inhabitants of Samaria" to describe the power center of the nation. Israel was sometimes called "Ephraim" after that prominent tribe. Samaria was the capital.

The people of Israel had grown proud and arrogant. Their nation had thrived for a season. The city of Samaria was said to be beautiful and luxurious. The Israelites foolishly believed they had built for themselves great beauty, wealth, and power. And that because of this false belief, they thought they could continue to live this way unchecked. They will soon know by the power of the destruction sent their way by God that the Lord is God.