The cuckoo apparently doesn't build its own nest, but waits for another bird to build one then hijacks it for itself. That's what came to mind when I heard about 'God' being dropped from the Girl Guides' promise recently.
This change was the subject of Nicky Campbell's phone-in show yesterday (19/6/13) on Radio 5 Live. The final call of the show was horrendous, but not as bad as Nicky's response!
I will paste my email I sent to the BBC today. In it you will get the gist of what the caller and Nicky said.