Our righteousness cannot come by obedience to the Law - this will only produce sin.  And since sin is the transgression of the Law, we know that we have to die to the Law and live by faith unto Christ as a means to be seen as righteous by God.  Those born again as God's children cannot sin because His seed is in us.  Sometimes our old nature revives and for a moment exerts its power.  But that is just the former man/woman and not our true identity.  The battle with the flesh is won through Christ and our identity will continue on after this life to God.  It is who we are - children of love.