Hi Expatbrit: I enjoyed your post and connect with the frustration you feel. I did not entirely read what other comments stated about this. You may first wish to try instead using questions that do not have any agenda. Draw out your relatives and seek their help. They will gladly do this.
Examples of risky vs safer approaches:
1. Direct Confrontation: "The Watch Tower Society flasly prophesied about 1914. They are liars and not from Jehovah!"
This type of direct approach will make you feel good right away, but the results will be like a spiritual hangover. This way almost never works.
2. Questions with an agenda: "So, tell me why the Society falsy prophesied about 1914? How can you possibly defend their actions?"
Here again, this is still much like the direct approach, but the question format is more rhetorical and demands the conclusion that they are worng. This is still too risky and will turn them off.
3. Question using vulnerability - what I call the Colombo Style: "Mom and Dad, I need you help on something. I am confused about 1914. The Society's older literature says that 1914 would bring Armageddon and it was the very end of the system, whereas the more recent literature says that they were fortelling 1914 to be only the beginning of the time of the end. Could you do some research and help me understand this difference? I would really appreciate your guidance because I want to understand the Truth."
This latter method is honest, allows you to convey the problem, but withholds judgment, agenda, and confrontation back so that your loved ones may think for themselves. As they do the research, and study the problem, they will see the contradictions and begin to see what the problem is.
It is still risky and could backfire as they read any 'attitude' into your sincere questions, but it generally is the least risky method. You don't have to use the 1914 issue, but I selected it for this discussion sake only. Oick an issue you are most confortable and conversant on.
Finally, keep the issue to ONE topic at a time! A barrage of several issues, even wrapped in gentle use of questions will cause them to feel you have an agenda, and that you are doubting enough that you are beyond their reach. By staying focused on one issue at a time, they are forced to deal with it. And maybe they will have some cognitive flare-ups that allow them to open up more. BUT ... be cautious about 'loyalty' questions from them, as this is a signla they are trying to smoke you out, and have no real interest in solving the problem.
Hope this helps. Let us know how it goes, regardless of which method you employ. - Amazing