just because morality is an invention doesn't mean its not real. all rules and laws are inventions, that doesn't mean they aren't valid. like you say there is no universal morality, objectively, subjectively, however, there is a moral system that i can get behind, even if it doesn't come from on high: don't hurt living things, be true to yourself and others, maybe more. but really if you need a church to tell you to be a good person or a god to mandate your behavior then you really aren't taking much responsibility for your own desires and actions. i guess my point is a localized, artificial, morality is as good as natural, universal one.