It's basically a protection racket for money and power. At least in the case of the catholic church. Yes they have zany stories about floods and people being made out of ribs, but a religion without such things isn't really a religion.
The Encyclopedia of Philosophy attempts to place the following extended definition upon it:
"
-Belief in supernatural beings (gods).
-A distinction between sacred and profane objects.
-Ritual acts focused on sacred objects.
-A moral code believed to be sanctioned by the gods.
-Characteristically religious feelings (awe, sense of mystery, sense of guilt, adoration), which tend to be aroused in the presence of sacred objects and during the practice of ritual, and which are connected in idea with the gods.
-Prayer and other forms of communication with gods.
-A world view, or a general picture of the world as a whole and the place of the individual therein. This picture contains some specification of an over-all purpose or point of the world and an indication of how the individual fits into it.
-A more or less total organization of one’s life based on the world view.
-A social group bound together by the above.
But fundamentally, the followers do conspire in the pursuit of their religion.
Converse case, many conspiracy theories are (or were) close to being religions....a perspective could be that, once a conspiracy theory gains state recognition, it becomes an established religion. Or once it reaches more than a certain number of followers.