How do Jehovah's Witnesses know that the book Vindication includes every revelation of truth?
Because the Watchtower magazine says so . . .
"The expression "the word", therefore, includes every revelation of truth down to and including the book Vindication" - 1932 Watchtower, April 1, pg.101, par. 13
How do Jehovah's Witnesses know that the Watchtower magazine is telling the truth about the book Vindication?
Because the book Vindication says so . . .
"The [Watch Tower] Society has been severely criticized because of the plain statements made in The Watch Tower and in its other publications concerning Satan's organization. These publications, however, must tell the truth, or else they will cease to be used by the Lord." - Vindication, pages 77-78
Evidently Jehovah's Witnesses also know that the book The Finished Mystery was permitted by Jehovah God to be published as the truth. How so?
Because the book Vindication, which has been verified by the Watchtower magazine, which in itself has been verified by the book Vindication, say so...
"It was then that The Finished Mystery was published; and God's purpose in permitting it to be published surely was for it to serve as an instrument to do a separating work that manifested the real heart condition of those who had professed to be in the covenant with him." - Vindication, page 265
And Jehovah's Witnesses all know that the 1917 book The Finished Mystery was inspired by God. How so?
"The milage from the Scranton to Hoboken Terminal is shown in time tables as 143.8 and this is the milage charged to passengers, but in 1911, at an expense of $12,000,000.00, the Lackawanna Railroad completed its famous cut-off, saving 11 miles of the distance." - The Finished Mystery, page 230
Thereby proving that the Lord's . . .
". . . guidance and help alone made this volume possible." - The Finished Mystery, page 230.