I was looking at the web site for the Brights, and found it amusing that there is a sub-section there for "enthusiastic Brights", given the definition of "a Bright" (in part: "A bright's worldview is free of supernatural and mystical elements"), and the etymology of "enthusiasm" (in part: "inspired by a god").
Captious comments aside, the site is interesting, and the list of enthusiastic Brights includes authors I enjoy reading.
OK, back to poking fun...
There has been some negative reaction to this nounification of the adjective "bright" due to the very strong positive meanings of "bright" as an adjective, especially with respect to intelligence. However, the use of "Brights" as a collective noun for people with a naturalistic world view is not supposed to imply people with other world views are dim or dumb any more than using the collective noun form "gays" for homosexuals (also derived from an adjective with positive meanings) is supposed to imply that others are dull, drab, dreary, glum or gloomy.
However, I just finished reading The New Hacker's Dictionary (3rd Edition):
(I've been reading it on and off for a few years now, but finally made the push to finish it a few weeks back).
While Paul Geisert and Mynga Futrell (the pair who in 2003 proposed this noun form of "Bright") haven't referenced it, this entry from the Jargon File points to an earlier (and harsher) use of "Bright" as a noun.