That's very perceptive. It's also something I've thought about before writing the article. Surely, any survey would be skewed by demographics. If we'd asked all the philosophers who go to church the same question, the numbers would be skewed the other way.
But I'd like to point to how we would have almost no issue identifying the "experts" of other fields like history and the sciences. In fact, we wouldn't have trouble identifying the expert philosopher who studies, say, ethics. Of course, we don't say that philosophers are experts on issues of morality, partly because it's one subject that has minimal consensus (almost everyone disagrees with one another).
Nevertheless, it's a question worth pondering. If we'd trust the doctor's opinion about our health conditions, what
s stopping us from trusting a philosopher's opinion on the nature of reality, the nature of science, and divine presence?