An atonement is an appeasement. It assumes that there is an offense, an offender, an offended party, and a moral obligation for a correction to be made to the end of restitution.
The offense is sin.
The offender is mankind.
The offended is God.
The moral obligation is wrapped up in the being of God Himself. It is His law written in our hearts. It is clearly defined in Scripture.
A correction is not merely a cancellation. Principles of bookkeeping are not isolated to the tracking of finances. Finances are tracked using basic principles of moral law. Restoration/correction must be made from somewhere. It costs something.
If the cash drawer comes up short at the end of the day, someone must make a correction to bring restitution to the accounts. It generally is the person responsible for the drawer. Occasionally without recognizing the example that they are, the store owner will take the damage upon himself.
Essentially God has taken the damage upon Himself when Jesus made an appeasement. Jesus took our shortcomings onto Himself.