Rick, I hear you, but respectfully disagree. There is ample evidence that people who believe pseudoscience and conspiracy theories without evidence also accept all sorts of other beliefs without evidence. And some of these beliefs may be dangerous, to themselves or to others (e.g., homeopathy). I don’t think you are doing a favor to your friend by indulging him. You could, however, politely decline, change subject, and invite him our for a beer. Still preserves your human relationship.