فِي ٱللُّغَةِ ٱلْإِنْجْلِيزِيَّةِ:

sometimes hyphenated or expressed as a phrase: poly-theists, poly theists
sometimes either the P or both the P and the initial T are capitalized: Polytheists, PolyTheists
variations of capitalization and spacing may be combined: Poly-theists, Poly-Theists, Poly Theists, Poly theists

polytheists