Why there is no supernatural morality: response to Miller's opening statement

If one is going to argue that objective morality depends on an Archimedean point outside the natural world, then it would seem to imply that this source is necessarily supernatural . Thus, Christian Miller begins by defining precisely who he thinks this supernatural moral law giver is: the omniscient, omnipotent, and omnibenevolent creator of the universe who is still actively involved with human affairs—Elohim, Jehovah, Yahweh, or Allah—aka God. Already I'm skeptical.