> If Christians went around calling Muslim's "Christ-deniers" instead of Muslims, how well do you think that would help tensions and resolution?

We could ask both of them to scientifically prove their faith and we’ll go with the successful one?

That’s facetious, of course, but it illustrates why this isn’t a valid comparison: religious faith is by definition dealing with things which cannot be measured scientifically while human-caused climate change has been the scientific consensus for half a century and has been rigorously tested using a wide variety of independent lines of evidence. Saying someone is denying that is valid because it’s a testable claim which can be rationally examined and independently confirmed, whereas a personal religious statement cannot because the successful religions in the modern era have evolved not to make claims which can be evaluated scientifically.