Temple fires inevitably sparked deep devotion among the Zoroastrian worshippers. Their purity within sanctuaries could be protected with a strictness not possible regarding hearth fires, and they were not only consecration at their installation, but were perpetually sanctified by prayers. Fires, bright and lively cons, attracted more veneration than idols of wood or stone. Gradually for each temple congregation their fire took on its personalized protective power. Herodotus (III. 16) speaks of the veneration of fire by the Persians, but he never specified it as the distinctive feature of their religion. It was only following the establishment of the temple fire that members of other religions labeled the Zoroastrians "fire-worshippers."
Although the Zoroastrian epithet of "fire-worshippers" may be said to be false by some, the mythology of fire is rarely represented in extant texts, there is still external evidence of an archaeological nature to prove the importance of fire in the cult. The essential sacrificial act of the cult, the sacrifice of the Yasna (sacramental liturgy), took place in the presence of fire. Also, the juridical oath is sworn by fire; shining in the night, fire hunts and destroys demons, and Iranian archaeology was studded with fire temples. Adding to the "fire-worshipper" tradition is the myth of Keresaspa, a hero of many exploits, who experience difficulty entering heaven because he once extinguished a sacred fire.
More evidence of the importance of fire within Zoroastrianism comes from the evidence of the existence of the "great fires," or the "cathedral fires," all of which were called Atar-Verethraghan, "Victorious Fires." These were created from the embers of many kinds of ordinary fires, purified and consecrated through prolonged rites. The lesser fires were simply called "Fire of Fires." These were composed of embers from hearth fires of representatives of each social class and their temples, equivalent of church parishes in Christendom. The reason for these great fires to be dedicated to Verethraghan is based on speculation; latter Pahlavi texts shows that all fires were regarded as warriors fighting for the spenta creation on both the physical plane against darkness and cold, but on the spiritual plane too fighting the forces of vice and ignorance. Therefore, not surprisingly, many of the great fires were devoted to Victory, and embers from them were carried before advancing the Zoroastrian army when marching to fight the infidel.