Sorry for not being round for so long, I will PM david and see if we can chat first.
Natural ethics for me is about "rational attraction to being", which means that we (ought to) live rationally (pursuing self interest as biological organisms), and this in turn is a form of attraction to being, in that it sustains our lives in a hopefully pleasing manner. So modern hedonism is flawed, because it all about the pleasure (which is part of attraction) rather than the objective side of adding adaptive, well adjusted extrenal actions. But it is an attempt at rational attraction to being, in that we are designed to pursue the ethical by evolution. Likewise I will argue that Christian ethics can be raitonal, but they may not be so self aware in the secular sense, just as there is discussion of life in the bible without modern scientific definitions of it.