Every Wind Of Doctrine.
It is a serious matter to represent God and Christ in one way, then find that our understanding of the major teachings and fundamental doctrines of the Scriptures was in error, and then after that, to go back to the very doctrines that, by years of study, we had thoroughly determined to be in error. Christians cannot be vacillating - 'wishy-washy' - about such fundamental teachings. What confidence can one put in the sincerity or judgment of such persons? --The Watchtower, May 15, 1976, page 298.
It can be said that Watchtower Society doctrine exists in a constant state of flux. Watchtower doctrine is fluid, but more than that, Watchtower doctrine often changes in a way such that new Watchtower doctrine actually contradicts previous Watchtower doctrine. In other words, what is taught and believed and held as absolute truth from God today, may be viewed as complete falsehood - complete "darkness" - tomorrow. Indeed, the wonderful "truths" brought to your doorstep by Jehovah's Witnesses today may in fact be in complete opposition to "truth" the next time the Witnesses show up at your door.
Click here to read the complete article from the WT Study site.