Sanctification is the process of dealing with changing the believer into an imitator of Christ. Justification provides a new position and not a new person. Justification is not a return to innocence. It is a state of righteousness not innocence. The fact that we have sinned and fallen so short is the basis for greatness of what God had done in justification.
Justification is a legal term and looks at the pronouncement of a verdict.
God declares the believing sinner righteous on the single condition of faith in His Son. It is a declaration of a verdict, not the infusion of a quality. It does not build a holy and righteous character in the believer. That word means satisfaction and through the ransom paid by Christ at the Cross to the Father, the Father's righteous demands were paid. Blood of the Cross refers to the sum total of the violent deaths experienced by Christ on the Cross.