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]