The following is from the book - AWAKENING OF A JEHOVAH'S WITNESS by Diane Wilson. (Chapter 7 'Truth or Consequences')
"The Society's claim that the organization represents the truth, but that the organization is also "progressive" (WT12-1-81, pp16,28), led to new meanings for 'truth': "present truth" (Rev - it's Grand Climax at Hand, 1989, p8), (WT 6-15-22, p187) and thus "past truth" and "future truth".
I heard talks in which Jehovah's "progressive" organization was likened to a beam of light along a timeline that illuminated the truth as time went on. Thus, today's truth could become tomorrows falsehood. Anyone staying in the "old light" behind the beam (by refusing to go along with the Society's changes in doctrine), or anyone who ran ahead of the light beam (by disagreeing with the Society and deciding for oneself what the truth was), were both viewed as being "in the darkness" and would be disfellowshipped. If a witness disagreed with any aspect of the current "light", and spoke of it openly or acted upon it, that person would be expelled from the organization. If however, the light beam progressed forward tomorrow to illuminate that person's viewpoint as really being the truth after all, the elders would not make any apology to that person, nor would any effort be made to reinstate that person back into the organization.
According to the Society's "progressive light" teaching, today's "present truth" could become tomorrow's "past truth"! In my opinion, that way of thinking negated the meaning of the word "truth". The whole "light beam" illustration did not make sense to me, especially since I knew that the Society often vacillated it's doctrines, at times returning to its former views which it had abandoned as "old light" and falsehood: thus, at times, the Society's "light beam" would seem to flash on and off, or even go backwards to illuminate the darkness it had left behind! Whether the Society changed a doctrine with a complete turn to the opposite view, and later returned to the original doctrine, then later again reversed itself, it always cited scriptural support for whatever view it held at the moment. No matter how many times the Society would change its doctrines, it forced Jehovah's Witnesses - under pain of disfellowshipping - to believe and teach its present view to be the absolute truth. The result was the some were wrong, and teaching falsehood, in order to be "right" with God.
..........Because the Society frequently changed many of its doctrines, often returning to views previously abandoned and then changing them back again, the situation got to the point where I had difficulty keeping straight just what the current teachings were on various doctrines. I felt angry that the Society, whose members led the organization that claimed to be God's channel, was so uncertain of what the truth actually was. It claims than no one can understand the Bible without its interpretations, but I was finding the Bible impossible to understand because of its interpretations.