I see that now.
Why do you say "direct" harm? Why can't a non-religious moral system take into account any harm, whether direct or indirect? Why would you need a god for that?
I don't think you've really explained your point. And the fact that non-religious moral systems (e.g. mine) can come to the conclusion that having sex with one's sibling is a bad idea seems to contradict your idea that you need religion to do this.
Can you expand on this? So far, your argument is less than clear to me.
Well, no, it doesn't follow.
I think you need religion if you're going to have a basis for religious rules, but not for morality. I can see how you need a belief in God to come to the conclusion "we need to pray five times a day and avoid eating pork", but I don't see how you need it to come to the conclusion "we need to help other people and avoid having sex with our siblings"... and I think the clearest evidence of this is the huge number of non-believers who are just as moral (and in some cases, more moral, IMO) than believers.
Perhaps I wasn't clear enough. I didn't say a non religious moral system can't take harm into account, rather I was saying that a non religious moral system, can ONLY take harm into account. (Even thats debatable but I won't dispute it, not now at least).
Sexual relations among the closest family members for instance, if it didn't involve penetration (therefore with no risk of pregnancy), would be perfectly moral in a non religious moral system.
In addition to incest, the same goes with open relationships, lying when no harm is done (say making up stories to make people laugh), no one can say they cause harm. So if someone is willing to say all of these examples are moral, then fine, you have a non religious moral system. Not one that I accept, but it is a system.
But I don't think one can accept certain things like open relationships on the basis that they aren't harmful, and reject other things like the ones mentioned that don't cause any direct physical harm, but are still immoral. Why would they be immoral? In such a system they would probably be more "pragmatic" than immoral.