Sin is only real to the mind that thinks it can be harmed.

Punishment is always the great preserver of sin, treating it with respect and honoring its enormity. What must be punished, must be true. And what must be true must be eternal, and will be repeated endlessly. For what you think is real you want, and will not let it go.      
                                                                                                                   

--- A Course in Miracles 19.3.2.4-7