Though, as Nat Irons put it, "It's pretty dead at the moment."

From PZ Myers, via Ezra Klein, on David Brooks and other conservatives using secular as if it means anti-Christian:

Ooh, there [Brooks] goes, treating some nice words as if they were smutty slanders. "Secular" is a virtue: we live in a secular state, which means it carries out its functions without requiring specific religious beliefs of its citizens. It does not mean that we hunt down and persecute Christians, much as the religious right would like you to think it is so.

So, let's check the official source for secular, shall we?

Main Entry: ¹sec·u·lar   
Variant(s): also saec·u·lar sekyl(r)
Function: adjective
Etymology: Middle English, alteration influenced by Late Latin saecularis) of seculer, from Old French, from Late Latin, saecularis secular, worldly, pagan, from Latin, coming or observed once in an age, from saeculum breed, generation, age + -aris -ar; akin to Welsh hoedl lifetime, Lithuanian sekla seed, Latin serere to sow -- more at SOW
1 a : of or relating to the worldly or temporal as distinguished from the spiritual or eternal : not sacred : MUNDANE <secular affairs> <secular occupations> b : not overtly or specifically religious <secular rites> <secular music> <secular drama> c : of or relating to the state as distinguished from the church : CIVIL <secular courts> <secular jurisdiction> <the champion of the secular power -- A.J.Toynbee> d : of or relating to the laity as distinguished from the clergy : NONCLERICAL, LAY <the secular landowners> <secular benefactors> e : not formally related to or controlled by a religious body <the greater number of secular than denominational schools in the country> f : rationally organized around impersonal and utilitarian values and patterns and receptive to new traits <our modern industrialized secular society> -- contrasted with sacred g : of, relating to, or advocating secularism : SECULARIST <an enlightened secular humanism -- H.N.Fairchild> <the disenchantment of absolute faiths which expresses itself in the secular outlook of modern man -- Louis Wirth>
2 a : living in the world : not living in a monastery or religious community : not bound by monastic vows or rules <a secular priest> <the secular clergy> -- opposed to regular; compare MONK 1 b : of or relating to clergy not bound by monastic vows <secular vestments>
3 [Latin saecularis] a : coming or observed once in an age or a century <secular phenomena> b : existing or continuing through ages or centuries : AGELONG, CENTURIED, DIUTURNAL <secular oaks> <secular enmities> c : of or relating to a long-enduring process <secular change> <regions of the earth's surface where ... slow secular movements of the crust are still in progress -- Endeavour> d : taking place within a century <secular fluctuation> <the secular variation in an astronomical position> e : requiring or taking ages (as for operation or completion) <secular forces> <the improvement of man is secular -- John Tyndall> f : of or relating to a long term of indefinite duration <the secular trend of prices> <a secular increase in the quantity of money is required in a growing economy -- Milton Friedman> -- compare CYCLICAL 2 g : recurring at intervals greater than one year <secular cycles in population pressure>
synonym see PROFANE

Citation format for this entry:

"secular." Webster's Third New International Dictionary, Unabridged. Merriam-Webster, 2002. http://unabridged.merriam-webster.com (8 Feb. 2005).
   

By the way, the Merriam-Webster Unabridged Dictionary Online is the best $30 per year a writer could spend - unfiltered access to the prescriptive dictionary of the American English Language. 14-day free trial, too. Go now. (I don't get affiliate money for this, I just really like it.)