The followers a a are obliged to believe it and so the faith, the creed of the Catholic Church then becomes an article of membership and if you don't subscribe to the creed, then this has implications for your standing in the group and you can for example be persecuted and  Catholics  not believing, whereas in a group like this, I don't think we need a creed, we certainly wouldn't persecute anybody because we didn't believe a particular thing, because we can all negotiate our personal relations face- to-face.