Mithraic
adjective
Mith·ra·ic mi-ˈthrā-ik 
: of or relating to a mystery cult for men of Iranian origin that flourished in the late Roman empire
Mithraism
ˈmith-rə-ˌi-zəm
noun -(ˌ)rā-
Mithraist
mi-ˈthrā-ist
noun or adjective 
Word History
Etymology
Late Greek mithraikos of Mithras, ancient Persian god of light, from Greek Mithras, from Old Persian Mithra
First Known Use
1678, in the meaning defined above