Think about it for a moment. 
@Martin Marprelate 
You believe that God took our sins (our past actions, our evil deeds we committed) and put thrm on Jesus to punish them there.
I stole a ball.  God took "stole a ball" from me and put "stole a ball" on Jesus.
God then punished "stole a ball" on Jesus.
That does not change the fact that I stole the ball.  I am still guilty.
So you say God took my guilt (my "having done it") and put "having done on" on Jesus and pretended Jesus did it.
Your theory does not work.  It sounds logical if you say it enough times and ignore reality.
1.  Sin and guilt are not material things.  One cannot take an action committed and put that on another person who did not do that action.  We are guilty because we did something.  That is not a material thing but a fact that we did an action. 
2. This does nothing to address the "old man".  You do not acceot the idea that we are made new creations in Christ (you continually go back to what the "old man" did, ignoring the "old man" no longer exists at Judgment).
BUT some Calvinists (probably moat) acceot that God has predestined us to be conformed into the image of Christ.
They still have a problem.  This means Christ's suffering the punishment of the "old man" had nothing to do with redemption at all.   The "old man" is NOT redeemed.  He dies and we are made anew.
Your view does not necessitate the cross in terms of redemption.  It does not need Christ to have died at all.
It merely needs God to have redeemed us through the law and given the law what it demanded of God.
Instead, Scripture presents Jesus as bearing our sin (not God pretending that Jesus sinned but Jesus actualky coming under the bondage of our sin), suffering and dying under this bondage, raising to live having conquered this evil and freeing us from its bondage, removing the "sting" of death, and becoming a life giving Spirit.
We do not need to play pretend.  God does not need to step away from reality.  Simply read the Bible and consider tge possibility that what God said happened and happens may really be true.