The first major promise broken by the god of the bible was that his promises wouldn't be broken. Even if the incredible happened and he delivered with the goods it'd be too late. He'd have already let much of his creation endure pain, agony and sorrow. A huge blemish on his character because he is 'eternal', and as such will have to face this eternity forever knowing of the suffering that his loved ones endured. A stain forever on his immortal mind... and therefore imperfect. An imperfect god can't exist (and so puff he goes in a cloud of logic).