Can the scientific method be used to test supernatural beliefs?

Depends. If you can somehow experiment on it, then Yes, it's possible. But the Scientific Method cannnot test "beliefs" of any sort. It can test hypotheses. So if your hypothesis is, for example, "There is extrasensory perception," you could develop a scientifically valid test of the hypothesis.

You would have to identify and control for variables and your experiment would have to be capable of duplication by other researchers. The results would have to be unambiguous, that is, not explainable by any alternate hypothesis. Hope we helped!