Take them to page 621 proclaimers book where it says
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jvchap.28p.621TestingandSiftingFromWithin***"As Jehovah’s Witnesses today review the work that he did, the things he taught, his reason for teaching them, and the outcome, they have no doubt that Charles Taze Russell was, indeed, used by God in a special way and at a significant time."
Ask them have they ever done this? Have they ever read any of the books and magazines Russell wrote? Maybe even mention
a tid bit of something Russell taught that most JW's know nothing about. Just enough to whet their appetite. Everything being hinged on
compliance with the above quote from the Proclaimers book. So you're not questioning the organization, you're following their direction.
See if they are willing to do what the Society says they as Jehovah’s Witnesses supposedly have already done.
Ask them to call Bethel and request some of Russells publications so they can be in line with what Proclaimers book.
Let them feel the shock of realizing they won't get anything of Russells from Brooklyn. If they are sincere they will want to do
the research on their own and you will be able to share what you have learned with them.