"Therefore, having been justified by faith, we have peace with God through our Lord Jesus Christ …" - ROMANS 5:1
Justification is an event. The moment you trust Christ for forgiveness your status changes in the Court of Eternity from guilty to innocent. Some think justification is a process. That view results in a life-long struggle to earn one’s own justification. There is no peace in that, only dread that one may not have done enough to appease the Judge.
God promises that when we are justified we have peace with Him, not because of what we do, but because of what He has done.