The Collaborative International Dictionary of English v.0.48:

establishmentarianism \es*tab`lish*men*ta"ri*an*ism\, n.
   the doctrine or political position that advocates
   establishment of a church as the official state religion; --
   applied especially to the Church of England..
   [PJC]

WordNet (r) 3.0 (2006):

establishmentarianism
    n 1: the doctrine of supporting the social or political
         establishment [syn: establishmentarianism,
         establishmentism]