Given the WTS constant indoctrination to "do more", I have had productive conversations with JW's about:
(1) Half the worlds population is not being witnessed to so how will God judge these people?
(2) Given people dont know much about JW's, will God judge people based on our 30 second magazine presentation and their reaction to that?
(3) Why is it urgent when God can read the heart of person?
Here is another argument to add to that list courtesy of Ray Franz on p460 of his book "In Search of Christian Freedom"
http://www.commentarypress.com/Publication/English.html
"In actuality, the lack of any formal program and the apparent spontaneity and individual motivation of the first century Christians are what are most remarkable in the accounts we do find in the Bible. We find only the barest of suggestions of what their meetings were like and no indication of any methodology or systematization in their proclaiming of the good news.
I recall that during the years I served in circuit and district overseer activity I used to puzzle over this when preparing the "service talks" that were a regular feature of the weekly program when visiting congregations. I wanted to prepare talks that were scriptural, but it seemed so difficult to find scriptures that even faintly reflected the kind of "organized service" urged by the headquarters in its publications. I found it hard to understand how the apostles Paul and John and the disciples James and Jude, could write entire letters to the congregations and never say anything stressing the need for the readers of those letters to get out and go from door to door, nothing about organised witnessing arrangements at scheduled times, about putting in more hours in the "field service" or similar approaches or topics, all things regularly stressed in the Watch Tower Society's publications. The letters of the apostles and disciples seemed deficient according to the viewpoint that had been developed in me.
It eventually became clear, after some decades, that the real problem lay with the viewpoint inculcated in me, a viewpoint that actually perverted the first-century record, manipulating it to make it say something it did not actually say. False deduction is employed. From the broad principle that all Christians should share the good news, deductions are made to support and cover virtually every aspect of the organizations systematised approach to worship and preaching. But those deductions are unjustified, as indicated by the absence of corroborative evidence in the Scriptures themselves. The systematised, highly programmed approach to Christianity that has developed bears greater resemblance to that of a large sales organization than to the first-century Christian congregation and its simple, uncomplicated approach to worship and service to God."