Isaiah 57:21 There is no peace, saith my God, to the wicked.
The wicked are all those that are still in their sins. You are still in your sins if you have not repented and turned to Christ. Wicked describes those that have not trusted Christ as their Savior. Wicked is one that thinks that they are fine by themselves in their own moral goodness.
They can never know when they have been good enough. They can never be certain that they are ok. They have to live in doubt and not peace.
You can know and have peace by trusting Christ as your Lord and Savior. Peace comes through Christ making peace for us. He paid our sin debt. He makes it possible for you to know that you are forgiven. Trust Christ today!