This post pulls out one strand from my argument here and makes it into an independent argument, under the inspiration of Chris Tweedt.
Valid commands are always to be understood in the context of a role, and give rise to a role-obligation in respect of the recipient's role. Thus, a military command gives rise to a military duty, a legal command gives rise to a legal duty, and so on. Divine commands also give rise to a role duty. Let's call this a creaturely duty. A military duty is the duty of the soldier qua soldier. A legal duty is the duty of a subject qua subject (one might prefer "citizen", but that's not right; I am not a citizen of the United States, but I am bound by its laws when living in the United States). A creaturely duty is the duty of a creature (or, better, rational creature) qua creature.
Now, here is a puzzle. Divine command theorists (of the sort that interest me here) tell us to understand moral duty in terms of divine commands. But what divine commands give rise to are creaturely duty. So why not, instead, define moral duty as creaturely duty—as the duty proper to our role as creatures of God—rather than as the content of divine commands? While all divine commands give rise to creaturely duties, it is not particularly plausible that divine commands necessarily exhaust creaturely duties. Imagine a world where God issues no commands, but Jones thinks that God (or: a loving God, if one prefers the Adams version) has commanded him to abstain from beef. Surely Jones has some kind of a duty to abstain from beef, and plausibly it is a creaturely duty. But there is little reason to think that among the creaturely duties only those that arise from divine commands are moral duties. It seems that what gives normative oomph to divine commands is that they generate creaturely duties. But if there could be other kinds of creaturely duties, these would then have the same normative oomph. And even if there could not be any creaturely duties other than duties of obedience to divine commands, it still seems that what does the explanatory normative work is not the command, but the creaturely duty that it gives rise to.
I think analyzing morality in terms of creaturely duty is superior to analyzing morality in terms of divine commands.
For instance, consider the worry that there are some actions that are so bad that they would be wrong even if they were not prohibited by God. There is at least some room for the response that these actions are, nonetheless, violations of a creaturely duty—maybe it is a part of the creaturely role that one not be nasty to those who are equally creatures.
Or consider the idea that God is morally required to keep his promises. While we don't literally want to say that God has a creaturely duty to keep his promises, that's just a matter of words. Let R be the creature-creator role. Then we can say that God has an R-duty to keep his promises (for us, R-duty is creaturely duty; for God, R-duty is creator duty).
I do not endorse the idea of analyzing morality in terms of creaturely duty, because I think all role duties are moral duties (though this controversial claim could be overcome).