Sin is not a thing in a box. Sinful choices no longer exist after the choice. They do not stay around to be left behind. Sin is not a substance or thing. Adultery is an act, not a literal 'thing'. We are justified in Christ, treated as if we never sinned. It is not a matter of reversing actual sins nor gathering them up in a bag to be thrown away. One act can be different than our standing. A believer can be in Christ, yet be sinful in one motive, thought, or act. If one is fornicating, they are not righteous in that one act, yet they are still in relationship with Christ.