It is interesting to note that according to freebase, the only religion that claims Earth as its place of worship is Yoism.

http://www.freebase.com/view/en/earth

It would seem to be quite accurate.
 
For the sake of argument, I think it is best to define religion as a particular system of belief. In this sense, atheism doesn't fall outside the boundary of religion even though they have no "theology" they do have a common system of belief - in some areas at least. this also means that Communism doesn't get a pass, nor do Apple fan boys.


For meaningful discussion, I think this is an important distinction to make.