Before moving on to something other than my nominalism about the word 'religion,' I'd just like to point out a few more problems with it.
First of all, 'religion' as the term is used in 'comparative religions' is relatively meaningless. If by 'religion' those who use the term mean one's view of the world, the ultimate reality, and human nature, then those who study comparative religions should study atheism, deism, the Transcedentalism of Emerson, hedonism, and all the other sorts of beliefs that have brought about comparative religious studies. If by 'religion' they mean any belief in something greater than man or existing on a level different from him, they still should study theosophy, fairies, UFO's, hero-worship, and other similar phenomenon. Either way, the term 'religion' is being used inconsistently. And the result of this inconsistent usage is that people separate themselves from what they are studying so that they think they have an objective, third-person viewpoint, when in fact the worldview from which they look at religion is just as parochial and limited a worldview as every other.
The other problem with the word 'religion,' unlike all those previously mentioned, comes from the internal perspective of those who might consider themselves religious.