Suppose the following epiphenomenalist thesis is true, at least for non-human animals: qualia do not affect behavior. It's interesting that if this is right, then the argument for atheism from animal pain is seriously weakened. The argument from animal pain contends that God would have reason to prevent many instances of animal pain that he does not in fact prevent. However, we have good reason to think that God's interventions would be targeted and hence minimal. Now a minimal intervention for the prevention of pain is simply to suppress the quale of pain. Given epiphenomenalism, however, suppressing a quale of pain does not affect either behavior or neural state. So if God thus intervened, things wouldn't look any the different. And hence the atheist cannot non-circularly deny that God did intervene to prevent the pain.
Of course, this might be taken to be yet another reason to deny epiphenomenalism.