It’s not every day you see an article in a theological journal by an atheist.
But lo and behold, the latest issue (downloadable here freely) of American Theological Inquiry includes a ‘guest’ article by Erik J. Wielenberg called “Objective Morality and the Nature of Reality”, which is a rejoinder to a theistic critique in a former issue. He calls his approach “non-natural, non-theistic, moral realism”. See for yourself, but when he goes on about “brute moral facts” and doesn’t seem worried that they are without any foundation, I just don’t follow him at all (not that I think the fellow he is critiquing has it sussed either).