Francoise, you say "I used to think the WTB&TS was just ignorant. Now I think they are evil, sinful, and iniquitous. On purpose." While I tend to agree with you, it is possible that one reason for inculcating hatred for 'outsiders' is the basic desire to keep the JWs united. If they are not united, the control of the Watchtower Society might be weakened, and that would never do. Of course, this goal is also, IMHO, extremely evil, but since the average JW has been taught to believe that unity is of primary importance, they probably do not see it in that light.
Farkel, one proven way of uniting people is by supplying a mutual enemy. Let's face it, during a war, people who are bitter enemies normally will suddenly become allies and pull together when facing a common foe. So stirring up hatred against non-witnesses is a logical step for the WTBTS.
esther