Some Thoughts Thereon...
Religion can be much more than just deistic thought (although that does play a part in most visible modern religions).
- Some might define Religion as a thought process imposed to bring concepts of morality and purpose into one's life, regardless of whether or not there's Good Ideas out there to sustain why this is. By that definition, many of the Factions could probably be classified also as religions.
- Religion is sometimes viewed as the ultimate guidebook on how you will live your life. In many cases this guidebook is written for you, as You are fallable, capable of error, and need a guidebook that does not have such things. Personal embellishments are pretty irrelevant for this stuff. (Hello, Strangevirus!)