I don't expect Christians to see God as a metaphor, but that's what he is. Perhaps it might be clearer to call him a character in fiction, and a very interesting one too: one of the greatest and most complex villains of all - savage, petty, boastful and jealous, and yet capable of moments of tenderness and extremes of arbitrary affection - for David, for example. But he's not real, any more than Hamlet or Mr Pickwick are real. They are real in the context of their stories, but you won't find them in the phone book.