Marlene Winell, an ex-Christian, in Leaving the Fold, wrote,
The most serious demand for unquestioned belief is, of course, the atonement. First the believer is to suspend familiar notions of justice, such as punishment for the guilty as opposed to an innocent party. You are then expected to accept the necessity of blood sacrifice for sin; that wrongdoing must be paid for, and not necessarily in proportion to the crime. A father’s sacrifice of his innocent son is supposed to be not only just but generous and wonderful. Then the temporary three-day death of this one person is supposed to wipe out all the wrongdoing and ineptitude of a species. And finally, you should believe that all you need do to erase responsibility for your actions and enter a haven of eternal reward is to believe. It’s no wonder that once a convert has wrapped his or her mind around this story, anything can be accepted as truth. The rest of fundamentalist doctrine can be easily swallowed, including Jonah. (Marlene Winell, Leaving the Fold)
This is great stuff, and concisely shows some of the insanity involved in believing the atonement to be a coherent doctrine and concept.