At least for the sake of earthly benefit, would that it were so... but I get a hunch that Mohammed, Anton LeVey, and several others haven't been tuning in to quite the same "ethical principles"
Yeah, they have to make it sound as "inclusive" as possible.
No, it does seem that the world's great religions do share similar moral principles -- it's a question of who the moral principles apply to, though. Islam makes a clear distinction between believers and unbelievers, between "us" and "them." Christianity, at least on paper, doesn't.