You're on it. you can't change someone's mind, only present information that contradicts their world view, and then it is up to them to process that change, or reject it. Introducing doubt.

An example from a blog on jewelry how to counteract astrological nonsense is to point out supposedly different stones like emerald and beryl, are actually the same mineral, just with impurities like chromium present.

By presenting neutral factual information in that fashion, you can ask how or why the chromium affects the spiritual flow of the thing or whatever. It remains up to the person if they are persuaded or not.