I read something about grieving today in the American Atheists magazine. It was something that Penn Jillette said. Penn is not exactly my favorite person in the atheist movement (far from it, actually), but I really liked what he said about grieving.
His observation was to this effect: if there is a god, then when your loved one dies you’ll wonder if you could have done more, prayed more to prevent their passing or reduce their suffering. I would add that if there is a god, s/he’s quite cruel for the way s/he takes certain people out of this world, and who wants to believe in a supernatural being that behaves like that?