"Whom have you so dreaded and feared that you have not been true to Me, and have neither remembered Me nor taken this to heart?" (Isaiah 57:11a) Who did they fear (reverence, stand in awe of, regard as supreme) more than the Lord? Did they fear their fellow man more than God and join in with idolaters in order to make treaties with them? If so, this is what the Scriptures say about that: "Fear of man will prove to be a snare, but whoever trusts in the Lord is kept safe." (Proverbs 29:25) "The Lord is my light and my salvation---whom shall I fear? The Lord is the stronghold of my life---of whom shall I be afraid?" (Psalm 27:1) If they had remained faithful to the Lord, no enemy could ever have defeated them.
Or perhaps they persisted in wickedness because they didn't believe the Lord would do anything about it. He says: "Is it not because I have long been silent that you do not fear Me?" (Isaiah 57:11b) They thought that because He did not immediately punish them for sins, He would never punish them. But the Lord, like a loving Father, appeals to mankind before taking punitive action because He does not want to have to be severe with us. He says: "Come now, let us settle the matter. Though your sins are like scarlet, they shall be as white as snow; though they are red as crimson, they shall be like wool." (Isaiah 1:18) He reasons with us first. He gives us several opportunities to repent of our rebellion. As the Apostle Peter said, the Lord is "patient with you, not wanting anyone to perish, but everyone to come to repentance". (2 Peter 3:9b) He doesn't remove sinners from the earth the very instant they reject Him because He wants them to be saved, not destroyed. But some interpret the delay in action as a lack of strength on the Lord's part or as a lack of morality on the Lord's part. That's why He asks the people of Isaiah's nation, "Is it because I have not already destroyed you that you think I will never discipline you?"
A lot of people think they are basically good people, even though they have not made God the Lord of their lives. They compare their morality to the morality of their fellow man and decide that they look pretty righteous in comparison to others. But we were never meant to compare our righteousness to that of our fellow man; we were meant to compare our righteousness to that of Almighty God! We will always come up short when we do that, which is intended to bring us to repentance so that our sins can be covered by the One who gave Himself for us.
The Lord will expose self-righteousness for what it is. "I will expose your righteousness and your works, and they will not benefit you." (Isaiah 57:12) We cannot obtain salvation by our own righteousness or by doing a lot of good works. Isaiah will say later in our study: "All our righteous acts are like filthy rags." (Isaiah 64:4) This doesn't mean that the believer isn't to do good works but that good works don't save us. We should do good works because we are saved, not in order to get saved.
The one who has trusted in his or her own works or who has forsaken the Lord for idolatry will reap what he or she has sown. "When you cry out for help, let your idols save you! The wind will carry them all off, a mere breath will blow them away." (Isaiah 57:13a) Idols are powerless. They will be no help to those who worship them. In contrast, those who trust in the Lord will inherit the beautiful things He has planned for His children. "But whoever takes refuge in Me will inherit the land and possess My holy mountain." (Isaiah 57:13b)