Leo, hmm... I see the point, but it's gotta be an error. It's a straightforward instance of the genetic fallacy to reason from "our moral intuitions have biological origins" to "therefore, it makes no sense to speak of 'moral duties.'" It might make no sense to speak of religious moral duties -- but surely that's because there's no god, and not because the source of our moral intuitions is otherwise. The quoted sentence seems to equivocate between religious claims of moral duty -- which was the topic of the rest of the surrounding paragraphs -- and [deontological?] claims about moral duty generally.