Given an average of 100,000 [EDIT 100,000 per month since 1937] civilian deaths at the hands of the imperial army just in China alone (there were civilians being slaughtered in Indo-china and the Korean peninsula also), if the bombs ended the war just two months earlier than it would have ended (incredibly unlikely to the point of absurdity), it was a net gain in civilians saved.

And it can be well argued that the Japanese civilian deaths should be blamed on the imperial army for not capitulating when it was obvious the war was lost.