All the wars in history suggest that folks don't use that "intrinsic" sense of right and wrong;scientifically it can't be shown to exist can it?
Wars are between groups. Right and wrong, for the most part, only operate within a group. Hell, even the Bible shows this. What about the war the Israelites waged upon the inhabitants of the Land of Milk and Honey just so they could take the land for themselves? Was that "right?" Of course, you'll say. God said it was right. But that makes right and wrong simply an opinion and not an absolute -- basically as arbitrary as you claim the morality of atheists to be.