I would suggest you invest in Don Cameron`s book "Captives of A Concept" that uses the WT`s own publications to debunk the thought that they alone were chosen as God`s mouthpiece in the time of the end..
I will put this in my own words however D.Cameron does a much better job of it.
J.W.`s teach that Jehovah /Jesus chose the International Bible Students Association as the only true religion in 1919 as taught by Charles Taze Russell and they were the faithful and Discreet slave Class to dispense spiritual food at the proper time.
Now think about this : Nothing C.T.Russell taught up until his death is acknowledged as truth by the JW religion today .
So if Jehovah / Jesus accepted what C.T.Russell was teaching back then as truth in the Watchtower and put their stamp of approval on it as the" Truth" and the faithful and Discreet Slave Class .
And it is now not accepted as "Truth" by the current Governing Body it either means Jehovah / Jesus got it wrong back in 1919
or else,
The current Governing Body of Jehovah`s Witnesses are Apostates rejecting Jehovah / Jesus appointing the IBSA /Jehovah`s Witnesses as the Faithful and Discreet Slave Class in 1919 .
They cant have it both ways.
That`s just one example their are many more gems in his book.