Phenomenal Conservatism and the Argument from Morality

I’ve never been a big fan of the standard argument for theism from morality, the one that argues that the existence of morality requires the existence of God.  But I think there are decent arguments that show that morality is a better fit in a theistic universe.  What do I mean by better fit? Quite a number of things.  For one of them, consider a story told by Phenomenal Conservatives that aims to justify moral realism.  

PC:  If some thing p seems to be the case, then that seemings-to-be gives us prima facie evidence to believe that p.  

Given this principle, a Phenomenal Conservative would argue from: It seems that it’s wrong to wantonly murder children, to; we’re prima facie justified to believe that it’s wrong to murder children.

Of course prima facie justification can be defeated.  We only have ultima facie justification if defeaters are lacking or if they fail.  It’s this stage of the argument that the truth of theism can be of use.  

There are a few alleged defeaters for moral realism, ranging from moral disagreement to evolutionary debunking arguments.  If theism is true, then we have a method open to us that allows us to debunk the evolutionary debunker--it seems plausible that a morally perfect God would want to give his rational creatures a moral sense even if God used evolution to create us.  

So theism allows us to answer at least one powerful and popular alleged defeater for moral realism, edging us a step closer to ultima facie justification.