I think we can be for sure, religious skeptic is an equally ridiculous term. It’s like saying I’m a teacup-around-Saturn skeptic. In any reasonable meaning of the word “certain”, “truth”, or “sure”, the teacup and any deity do not exist nor play any role in our lives. They deserve no consideration except for niche discussions in philosophy and epistemology. We should use the teacup example even in that case, not the deity one.