Why not put new information out there that they can accept and let them do what they want with it? Why not even defend and reason on what could later be justified in there own minds?
That's what I've been doing with a lot of JWs including hubby and it seems to have the greatest affect without them putting there defenses up.
For example, I said to hubby the other night regarding blood fractions: "I dare you to raise your hand and say: So, clearly, the symbol of life is much more important then life itself." He wouldn't do it. Why? Cause something didn't seem right about that.
Another example: My mom said that now MJ has a chance at the resurrection. I said, "Well, it's a good thing he died then!" She fumbed over her words a bit but I bet she thought about it!
Hubby felt guilty about us fornicating before marriage. I showed him other bibles where it said that was ok as long as you get married. I showed him the scripture and said "Do what you want with this information." He very happily accepted that as truth.
The point being is to actually go along with what they say but at the same time giving them things to think about... I think this helps not to bring defenses up.
Defending what could be later justified in there own minds regarding JWs:
Case in point: Hubby brought up how MJ could no longer talk to LaToya cause she was d'ffed and how he didn't agree with that. I said, "Well, LaToya could be lying." He said, "Yeah, that's true!" I said, "However, that is a plausible situation considering how JWs can't speak with d'ffed ones."
Any other ideas?