An interesting read on the decline of the Christian Scientists (CS) .
https://www.theguardian.com/world/2019/aug/06/christian-science-church-medicine-death-horror-of-my-fathers-last-days
Re JWs , from a quackery pseudo medicine / religion standpoints , thankfully the crazier Woodworth / Rutherford anti vaccination etc inspired medical nonsense was mostly ditched in the 50's and 60's. The ban on transplants was ditched more recently. The only residual health related teaching remains the ban on blood transfusions , but even that has been watered down with the Society permission now granted to use blood fractions , new technology ( like cell savers ) and even whole blood products like hemoglobin.
Otherwise seeing the way a late 1800's USA religion declines is of interest. The CS leadership have faced the same challenges as JWs and have tried to cope with them in a very similar way. The young people stop attending , the general public are much more informed so very few new people enroll , the church is hit by lots of child abuse lawsuits and with the finances drying up , it relies on real estate development to keep going. Congregations are merged , halls are sold off , new properties are developed with mainly volunteer labour and then flipped for big tax free profits a few years later.
In many respects , the CS church in 2019 is probably where one imagines the Society will be in 20 years time.