Wallace Stevens has a collection of essays called The Necessary Angel. I have always liked the title. I personally do not believe in angels (I am Buddhist) but I do believe in the need for angels and such. To be human is to use the imagination. I am all for the imagination (it is only when angels interfere with the our lives of many that I see a problem).
God is a metaphor. What I mean by this is that Christians use God to present their beliefs. And as a Buddhist I use Buddha and Bodhisattvas to present mine (Buddha is a metaphor). It is not a question which is correct but that what is exactly being presented that is important. We need to put our ideas in some kind of concrete way (we have no choice) and no better is it to personify our ideas and concepts.