Robert Heinlein on metaphysics

Robert A. Heinlein, in his book To Sail Beyond the Sunset has the main character, Maureen, state that the purpose of metaphysics is to ask questions: Why are we here? Where are we going after we die? (and so on), and that you are not allowed to answer the questions. Asking the questions is the point for metaphysics but answering them is not because once you answer them you cross the line into religion. He doesn't really say why but the answer as to 'why' is obvious: because any answer is an opinion. It may be a good opinion, or a bad one, but it's only what the person who wrote the opinion believes. Such opinions cannot be validated, e.g., you can't ask the person to show you what it's like after death or provide for a personal audience with to their God or gods.