"Is God Necessary for Explaining Moral Absolutes?"

Joe Carter links to Matthew O'Brien's Public Discourse essay, which answers this question "yes."  Recognizing that some people who are much smarter and more learned than I am think that the answer is "no," I am inclined to agree with O'Brien.  It's not (as I see it) that claims about what ought or ought not to be done -- or even about what absolutely ought or ought not to be done -- are not rational or reasoned; it's that (as I see it) God's existence and providence, His creating and sustaining of the world, His gift of dignity to and plan for human persons, etc., are what make it the case that it is true -- that it is even possible for it to be true -- that some things really ought or ought not to be done.  It seems to me that, if "the world is made up entirely of physical particles in fields of force," then there are no "moral absolutes"; it makes no sense, really, to talk about what meat puppets really ought or ought not to do.  It's because we are not just meat puppets, but rather creatures of a loving God, that it does make sense to talk about these matters.

Alright, philosophers.  The comments are open.  Set me straight.

UPDATE:  Sam Levine (Touro) kindly suggested to me that these two earlier MOJ posts (from 2008 and 2009) are relevant to this discussion.  Sam wrote:

Some Jewish biblical commentators understand Abraham's statement in Genesis 20:11 as making a similar point about religion and self-control. In the context of the narrative, Abraham seems to imply that notwithstanding the possible virtues of Abimelech and the people of Gerar, the lack of religious belief left them (relatively) vulnerable to temptation and improper

Another update:  Robert Miller, at First Things, contends that "moral absolutes" do not depend on "divine commands."  He concludes:

Some actions are incapable of being ordered to our final end, and these actions are always and everywhere wrong. God absolutely prohibits such actions, but the divine legislation functions not to ground the absolute prohibition but to enforce it.

And here comes the unfrozen caveman lawyer (i.e., me) obstinately wondering whether it would make any sense, really, to talk about "final ends," and about the always-and-everywhere-wrongness of actions that are "incapable of being ordered" to them, if there were no God.  If the universe were as, say, Searle describes it, then there would be no "final end" of persons (indeed, there wouldn't really be "persons") and no "moral absolutes."  To say this, though, is not (at least, I think it is isn't) to embrace "divine command" theory; it is to say, though, that theism is necessary for morality to be real. 

I know, I know.  A lot of really learned people say I'm wrong about this, and so I guess I am.  But, I suspect that I am invincibly so, because I cannot shake my attachment to what seems to me obvious:  Happen-stance clumps of electrified bits of dirt don't have morally meaningful "final ends"; creatures of a loving God, however, do. 

YET ANOTHER UPDATE:  A friend and reader helpfully sends in this quote, from Peter Atkins (a chemist):  “I adopt the view that the whole of all there is can be accounted for by matter and its interactions.”  As I see it, if Atkins's view were true -- that is, if it really were the case that "the whole of all there is can be accounted for by matter and its interactions", i.e., if there were no God, then it would not make much sense to talk about "moral absolutes" (or morality, for that matter).