One of the most common objections to the ransom theory of the atonement is that it portrays God as a deceiver, and hence directly perpetrating an immoral action. This objection is utterly uncompelling for a number of reasons, not the least of which is the fact that not all acts of deception are immoral. Arguably, some are even morally obligatory.
Granting this, the objection may actually serve to highlight a strength of the ransom theory in the following way: the model fosters a powerful image of ultimate poetic justice, where God deceives the Deceiver. God beats Satan at his own game, and does so by taking the hard route of deceiving him in a morally permissible (perhaps even obligatory) way.