Active disbelief? that was my M.I.L. about 30 years ago. She joined a group out in the San Francisco area called. "Christian Prophets of Jehovah". Megaphones
at the conventions, disrupting bookstudy conductors. Quite a stir back then.
From my observation at the local hall, I have not observed any open display of disbelief. What I have observed over the years is the loss of all the young people. Every teenager from the 90's had faded, or got disfellowshiped minus one, an elders son.
The mike rovers consist of 60- 70 year old elders. More subtle yet blatantly observable is that there are 8 former pioneers,elders and ministerial servants that attend but no longer comment or go out in service. It is a strange sight to see 40 and 50 something year old former elders and ministerial servants sit and watch the old guys not only roving but answering most of the questions. There have been no teenagers at the hall for about ten years. 4 couples w/children now.
It has gotten so bad that they recently recruited two pioneer couples in their early 30's to 'assist' the congregation. They have also been recruiting speakers from over 100 miles away and other states to fill in the talk schedule the past 6 months.