What does Isaiah 26:10 mean?

The Lord God of Israel is both righteous and merciful. He uses His might to bring both grace and justice (Isaiah 26:8–9). Now Isaiah declares that the Lord's judgment on those who do evil is a better teacher than His mercy. Those who flaunt His commands don't respond to His restraint (Psalm 10:13). Unless evil people are held accountable for their actions, they won't come to understand God's true greatness (Proverbs 5:22–23). Those who do evil won't understand what it means that the Lord is righteous in all that He does.

The result is that even in a culture steeped in goodness and truth, the wicked will not change their behavior to fit in with those who follow the Lord's ways. They don't recognize how majestic God truly is (Psalm 14:1). They do not bow to Him or live as if His revelation to them is meaningful. They continue to follow their own way and live their own corrupt lives.

In the following verse, Isaiah will call for the Lord to bring that judgment sooner than later. He asks the Lord to show the earth His righteousness by punishing those who do evil and vindicating His own people in the process (Isaiah 26:11).