before vowels pyr-, word-forming element form meaning "fire," from Greek pyr (genitive pyros) "fire, funeral fire," also symbolic of terrible things, rages, "rarely as an image of warmth and comfort" [Liddell & Scott], from PIE root *paewr- "fire." Pyriphlegethon, literally "fire-blazing," was one of the rivers of Hell.
word-forming element meaning "worship of," used as an element in native formations from 19c. (such as bardolatry), from Greek -latreia "worship, service paid to the gods, hired labor," related to latron (n.) "pay, hire," latris "servant, worshipper," from PIE *le- (1) "to get" (see larceny).
<a href="https://www.etymonline.com/word/pyrolatry">Etymology of pyrolatry by etymonline</a>
Harper, D. (n.d.). Etymology of pyrolatry. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/pyrolatry