The Collaborative International Dictionary of English v.0.48:

Sectary \Sec"ta*ry\, n.;pl. Sectaries. [F. sectaire. See
   Sect.]
   A sectarian; a member or adherent of a sect; a follower or
   disciple of some particular teacher in philosophy or
   religion; one who separates from an established church; a
   dissenter.
   [1913 Webster]

         I never knew that time in England when men of truest
         religion were not counted sectaries.     --Milton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sectary
    n 1: a member of a sect; "most sectarians are intolerant of the
         views of any other sect" [syn: sectarian, sectary,
         sectarist]

Moby Thesaurus II by Grady Ward, 1.0:

126 Moby Thesaurus words for "sectary":
   Bohemian, Maecenas, Young Turk, abettor, adherent, admirer,
   advocate, aficionado, alienated, angel, antiestablishment,
   apologist, apostate, appendage, at odds with, at variance with,
   attendant, backer, beatnik, bigot, breakaway, buff,
   cavaliere servente, champion, cohort, counter-culture, courtier,
   dangler, defender, demurrer, denominational, denominationalist,
   dependence, dependent, deviant, differing, disagreeing, disciple,
   dissenter, dissentient, dissenting, dissident, dropout, encourager,
   endorser, exponent, factional, factionist, fan, favorer,
   flower child, flunky, follower, following, freak, friend at court,
   hanger-on, henchman, heretic, hippie, homme de cour, in opposition,
   interested, liberal, lover, mainstay, maintainer, maverick,
   misbeliever, misfit, nonconforming, nonconformist, nonjuror,
   objector, opinionist, opposing, opposition voice, original,
   paranymph, parasite, partial, partisan, party, patron, promoter,
   protagonist, protestant, protester, public, pursuer, pursuivant,
   radical, rebel, recusant, reliance, revolutionary, satellite,
   schismatic, second, seconder, sectarian, sectional, separatist,
   shadow, sider, sponsor, stalwart, standby, stooge, successor,
   support, supporter, sustainer, swinger, sympathizer, tagtail, tail,
   trainbearer, ugly duckling, unconformist, underground, upholder,
   votary, ward heeler, well-wisher, yippie