What Does Theism Add to Ethical Naturalism?

Recent literature seems to have opened up space for naturalistic theistic metaethics in a contemporary context, as proponents of divine command theories have tended to be restricted to either supernatural or theistic non-natural theories within existing taxonomies of normative theory. While perhaps encouraging for theists, would theism add anything substantive to theories of ethical naturalism? In this paper, I examine this question. I argue that theistic naturalism appears to incur certain objections as well as provide a plausible and explanatory constraint on content for theories of ethical naturalism. As a result, a corresponding challenge to non-theistic variants is raised.