Why do Jehovah’s Witnesses believe that only …?

QUESTION: Why do the Witnesses believe that ONLY those who are part of the organization will be the ones who make it through Armageddon? Do you believe that one must be a part of the organization in order to make it through Armageddon? A recent WT stated that ONLY the incorrigibly wicked would be destroyed. Are the Witnesses the only ones who fall into that category?