Maybe just asking for explanations is the best bet?

"I don't understand the mechanism by which God could make something right or wrong."

"Even if I accept that God must exist, I don't understand where Jesus enters into things"

"If the Catholics have it right, why don't they do any better than the rest of us ethically?"

"The only evidence you have for God is a feeling that morality must have certain properties. What would constitute evidence for or against your views on morality? And if there is no evidence, why believe one way or the other?"