According to the 1985 Awake! magazine, Jehovah's Witnesses believe that the Bible is complete.
*** g85 12/8 pp. 16-17 The Bible—Do We Have All of It? ***Yet, when students of the Bible under your tutelage advance through the stages of indoctrination in accordance to your teachings, you introduce a new concept to them somewhere down the road during your "public meetings" and through more advanced publications, something called "progressive revelation", a term you've never actually defined for your members.
"Jehovah’s Witnesses believe that the Bible is complete."
*** w94 3/15 p. 12 par. 11 Jehovah The God of Purpose ***Isn't it true that the "progressive revelation" you speak of is, in fact, a concept that suggests that God reveals "truth" progressively through certain divine messengers over time and that this revelation is adapted to time periods and places where they are revealed, even giving new meaning to old prophecies and other Biblical principles, a concept that originated in the 1800's in Persia by a religious movement called the "Bahá'í Faith"?
Therefore, down through the centuries, he has progressively revealed his purposes to his faithful servants.
*** yb75 p. 145 Part 2—United States of America ***
"Jehovah certainly blessed his people back in the 1920’s and provided
the things they needed to advance the interests of the Kingdom. He also proved himself to be a God of progressive revelation."
The channel today that you claim God is using would be the organization that you, The Watchtower Society, are the figurehead of. So, two tenets your members are "encouraged" to accept are 1) that the Bible is complete and that God has provided man with everything necessary for life and knowledge about Him, but 2) that you, The Watchtower Society, must reveal "progressive revelation" to your members as divine messengers of yesteryear have done, working hand in hand with God Himself in enlightening mankind with spiritual insight that you have labeled "new light" - mankind that you have stated repeatedly has been trapped in satanic darkness for thousands of years. That's quite a tall glass of water that your members are "encouraged" to drink after being told for a great portion of their recruitment that all that is necessary for living and learning about God is the Bible.