Religion is not often about intelligence or being smart. The human personality is a spectrum and it can choose to go in any direction that is convenient. You can be a Nasa scientist and still leave you brain at home when you go to church or the KH because you are in the presence of a greater being.
Most JW don't understand their teachings for the simple reason that when you start to question things that do not make sense, you are told to leave it in Jah's hand. After a while, you just go with the flow because it is easier to be at the same intellectual level as those in your social group.