But after they had rest, they did evil again before thee: therefore leftest thou them in the hand of their enemies, so that they had the dominion over them: yet when they returned, and cried unto thee, thou heardest them from heaven; and many times didst thou deliver them according to thy mercies; and testifiedst against them, that thou mightest bring them again unto thy law: yet they dealt proudly, and hearkened not unto thy commandments, but sinned against thy judgments, (which if a man do, he shall live in them;) and withdrew the shoulder, and hardened their neck, and would not hear. Yet many years didst thou forbear them, and testifiedst against them by thy spirit in thy prophets: yet would they not give ear: therefore gavest thou them into the hand of the people of the lands. Nevertheless for thy great mercies’ sake thou didst not utterly consume them, nor forsake them; for thou art a gracious and merciful God. – Nehemiah 9:28-31
The Levites continue their prayer reminding themselves, as they speak to God, that their historical pattern of disobedience was a chronic problem. They did not disobey just once or twice over the years. They had a habitual pattern of taking the mercy of God for granted. After receiving blessing from God, they would, time and again, disobey and reject His law and counsel.
So why did God not just wipe them off the face of the earth?
Mercy is not getting what you deserve for bad behavior. They disobeyed. Therefore, they deserved destruction. Instead, they received mercy in the form of chastisement and deliverance, every time. And that is the key. There is not end to the mercy of God toward His people!
We need to not make excuses for our sins. We should confess them and take full responsibility. After all, God knows even the thoughts and intents of our hearts. He can tell before we lie to Him! But the joy that is found in the gospel is that we are coming to a merciful Father, not a tyrant judge.
But we are all as an unclean thing, and all our righteousnesses are as filthy rags; and we all do fade as a leaf; and our iniquities, like the wind, have taken us away. – Isaiah 64:6
This I recall to my mind, therefore have I hope. It is of the Lord’s mercies that we are not consumed, because his compassions fail not. They are new every morning: great is thy faithfulness. – Lamentations 3:21-23