People always ask what subject they should raise with their JW relatives. The problem is, what is important to you is often of no consequence to me. No one knows what will be THE ISSUE to change a relatives mind. If you raise doctrine, they will have some arguement, if you raise a controvesy they will deny it.
In another thread someone recently said "Why should we have to prove anything to them, make them prove it to us" What a great point. Put the onus of proof on the JWs. In legal circles you do not want to be the person that has the onus of proof on you, as then you have to do all the hard work proving something.
You could start with "I don't want to discuss doctrine. There are sincere scholars in every religion that say their doctrine is correct and have lots of scriptures to back it up. I am not a scholar, I don't really know which one is more accurate"
So here is the question;
"Mum/Dad/Sis, I need you to prove to me that God chose the Watchtower Society to be the only acceptable religion in 1919? I can't see any real scriptural indication that there would be a new organisation start in the last days that a person has to be part of or that it would be in 1919."
Could that work, and is there anything else that can be added?