For as through the one man’s disobedience the many were made sinners, even so through the obedience of the One the many will be made righteous. (Romans 5:19 nasb)
By Adam’s one act of disobedience, many—that is, all—of his descendants were made sinners. But by Jesus’ one act of obedience, all who believe in Him are made righteous.
The parallel is important because the people who became sinners as a result of Adam’s sin, including you and me, were not just sinners by label; they were sinners by nature and by act.
Correspondingly, when we are made righteous through faith in Jesus, it is not that God just puts a new label on us by taking away the label “sinner” and applying the label “righteous.” Rather, we are actually made righteous, by nature and by act.
Just as surely as Adam’s disobedience made us all sinners, in exactly the same way, Christ’s obedience can make us all righteous. Not just in theory, not just in theology, but in the way we live—in the very nature that is in us.