From spirit + -istic.

• (RP) enPR: spĭrĭtĭsʹtĭk, IPA: /spɪɹɪˈtɪstɪk/

spiritistic

1. Of or pertaining to, or associated, dealing, concerned, or connected with, spiritism (a.k.a. modern spiritualism); spiritualistic.
   • 1867, England’s Leader^?, 15th June 1867 issue, page 333, column 1

     That spiritistic ‘literature’ which has led astray…so many weak and impressionable minds.

   • 1880, William Dean Howells, chapter 4, in The Undiscovered Country, page 70:

     The only perfectly ascertained fact of spiritistic science is the rap.

   • 1898, The Popular Science Monthly, volume 52, page 493:

     New support for unfounded spiritualistic and spiritistic chimeras.