Hi!
Yes, it is true that Jehovah's Witnesses are in a cult. However, broadsideing them with all twenty-one guns at the same time is probably not the wisest approach. Such passion as demonstrated by Coral Snake is, in my experience, usually associated with someone who has either had first-hand exposure to the teaching in question or has had a loved one involved in such teaching. And, who can blame them? After all, they have been deceived and have experienced the results of such deception. May I also add that we have all, at one time or another, been deceived.
Personally, I almost always invite JW's in for a discussion. Before they leave I always ask them about John 1:1. They seem to have no answer. They seldom come back, much to my regret. So, I try to get them thinking for themselves by presenting inconsistantcies in their own teachings. Also, I add their names to my prayer list. After all, it is only God who can save them.