I've noticed a lot of ex-jws having their one issue.
For some it seems they would still be a jw but they found out about molestation cover ups and left.
Others have their one scripture that they found was misquoted and left.
Some read a science book and found the jw line of thinking a bunch of hooey.
I left thinking it was still "the truth" but when I found out about 1914 it resolved all remaining belief in me.
I guess I'm saying that I'd approach it from the angle that there are multiple reasons to leave and they are all good.
Now my arguement against the jws is that this is the year 2014 and its a dead religion. Every reason I heard while growing up that its the true religion has run its course and proved wrong. The generation that would not die is dead and any talk of "overlapping generations" is a bunch of nonsense.