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]