Gee, if reasoning alone could do it, we could empty the Kingdom Halls tomorrow. I like Steve Hassan's picture of two persons imprisoned inside the cultist; the natural person and the put-on personality. Scare or antagonize the cult personality, and they will fight you to their last brain cell. And there won't be many working at that point. All you will get is the rehashed doctrine repeated ad nauseum.
If you can address a person naturally, they may hear you.
I think this is what makes a JC a lose-lose proposition. There may be an elder in a receptive mood, but the cultic majority will always dominate. All you can hope for is a seed of doubt to be planted, to bear fruit who knows when? You certainly won't win any "argument".
Who wants to lob words at one another? I'd rather be heard.