The Collaborative International Dictionary of English v.0.48:

Pantheistic \Pan`the*is"tic\, Pantheistical \Pan`the*is"tic*al\,
   a.
   Of or pertaining to pantheism; founded in, or leading to,
   pantheism. -- Pan`the*is"tic*al*ly, adv.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pantheistic
    adj 1: of or relating to pantheism [syn: pantheist,
           pantheistic]