The Collaborative International Dictionary of English v.0.48:

fundamentalist \fundamentalist\ fundamentalistic
\fundamentalistic\adj.
   1. of or pertaining to fundamentalists or fundamentalism.
      [WordNet 1.5]

   2. characteristic of a fundamentalist; -- especially,
      resembling the behavior of a fundamentalist; as, a
      fundamentalist dislike of new ideas.
      [PJC]

WordNet (r) 3.0 (2006):

fundamentalistic
    adj 1: of or relating to or tending toward fundamentalism [syn:
           fundamentalist, fundamentalistic]