That would be more like if the JWs broke up into several denomonations or sects, something the GB doesnt want. There are different denominations in Judaism (or movements as they're called). Ultra Orthodox, modern orthodox, reconstructionists, conservatives, and reform. The orthodox share the same JW mentality of being seperate from the world, not associating very much with those outside the religion, and wanting to follow the Bible very closely, while reconstructionists are those that don't believe in the supernatural, but like to follow and preserve a Jewish lifestyle.
It is still possible for someone to go to church or be part of a religious group without believing in it. They may just want to join because of social reasons and connections. That would make them "institutionally religious."