At first, I didn't want to overwhelm them with the dirty laundry of their faith, so I attributed mistakes in their theology to other religions. Of course, they laughed. They honestly believe that the scientologists believe that organ transplants were akin to cannibalism and how they predicted the end of the world to be in 1874 and they had a good time laughing at that cult.
This is brilliant! What an excellent way to criticize Witness beliefs without them immediately ending the discussion. It reminds me of the prophet Nathan telling King David the story about the poor family's little lamb that was taken and slaughtered by the rich man.
Did you ever reveal to them that these were Witness beliefs? How did they react?