God's righteousness is given to us by God in Christ. It doesn't matter if our minds or the Devil accuse us of sins. It doesn't matter if others remember what we were like in the past. God sees us as perfectly righteous not because of what we have done, but because of what His Perfect Son did for us!
Why do we always make the Gospel more difficult than it is? The Gospel is the Good news that Jesus Christ died, was buried, and rose again and we can receive eternal life not through any works - but solely by God's grace through faith in Him!