I guess we would admit morality could exist without God, but absolute morality would not. Human morality would be relative to the convention it exists in and not absolute. I do not have to explain the problems that would exist in this paradigm (Hitlers Germany for one). How about a scenario of dwindling resources where certain parts of the human populations are "expendable" etc etc etc....Morality would have to have a source outside of human existence to have any authority over human existence, wouldn't you think ?