blondie, the change from "not a religion" to "a religion" is interesting. It was obviously a holdover from Rutherford's "a snare and a racket" that they didn't use the term for themselves. So why, a bit after Rutherford was safely off the scene, did they suddenly allow themselves to be labelled as such?
A guess would be that the perpetually smoking gun of their charitable status (thanks to Vidiot for constantly pointing that out) is involved. That for registration as a 501c charity, (or to register with some other government body) they needed to use particular wording, religion being one such word. The word was going to show up on searchable documents, so they wisely announced their change of tack.
They did something similar in the 90s with the whole UN thing, but interestingly, weren't as forthcoming, and got caught.
Why did they make an honest change in the 50s, but didn't do so in the 90s? In the 80s or early 90s they could have had new light that the UN was not the beast after all, and then them writing positive articles about the UN wouldn't have been so jarring.