Qos (Hebrew קוס/קוש), also Qōs, Qaus, Koze) was the national god of the Edomites. He was the Idumean rival of Yahweh, and structurally parallel to him. Thus 'son of Qōs' parallels the Hebrew 'Beniyahu' (son of Yahweh). The name occurs only once in the Old Testament (if we exclude a possible allusion in an otherwise corrupted text in the Book of Proverbs) in the Book of Ezra as an element in a personal name, Barqos ('Qōs gleamed forth'), referring to the 'father' of a family or clan of Edomite nĕtînîm or temple helpers returning from the Babylonian exile. The noun frequently appears combined with names on documents recovered from excavations in Elephantine, where a mixed population of Arabs, Jews and Idumeans lived under the protection of a Persian-Mesopotamian garrison.
Origins, meaning and cult
Qōs may mean bow. It is speculated that this god may have been interchangeable with Yahweh, Baal, Haddu/Hadad and Dushara, these five names being epithets for a common deity. Unlike the chief god of the Ammonites (Milkom) and the Moabites (Chemosh), the Tanakh refrains from explicitly nominating the Edomite Qōs and Yahweh hailed from Se'ir in the region of Edom. The omission may be explained, according to some scholars, by the close similarity of Yahweh with Qōs, making rejection of the latter difficult. Both Qōs and Yahweh are probably words of Arabic origin, and Knauf and others argue that YHWH is a northern Arabic word, from the Semitic root hwy, meaning "he blows". Knauf concludes that the two are typologically similar, being:
forms of the Syrian-Arabian weather-god, among whose attributes the bow is as much a part of as the storm.
Recently the view has been advanced that Yahweh was originally an Edomite/Kenite god of metallurgy. According to this approach Qōs might possibly have been a title for Yahweh, rather than a name. A further point connecting Yahweh with Qōs, aside from their common origin in that territory, is that the Edomite cult of the latter shared characteristics of the former. Thus we find that Dō’êḡ the Edomite has no problem in worshipping Yahweh, he is shown to be at home in Jewish sanctuaries, circumcision was practiced in Edom. Qōs became identified with Quzah, "the archer" in the north Arabian pantheon, worshipped both as a mountain and a weather god. The similarity of the name would have permitted an assimilation of Qōs to the Arabian god of the rainbow, qaws quzaḥ.
The worship of Qōs appears to originally have been located in the Hisma area of southern Jordan and north Arabia, where a mountain, Jabal al-Qaus, still bears that name. He entered the Edomite pantheon as early as the 8th century b.c. M. Rose speculates that, prior to Qōs's advent, Edom worshipped Yahweh—a connection going back the early Egyptian references to YWH in the land of the Shasu—and the former then overlaid the latter and assumed supremacy there when the Idumeans lost their autonomy under Persian rule, perhaps compensating for the destruction of national independence, a mechanism similar to that of the strengthening of Yahweh worship after the fall of the Jewish kingdom. Qōs is described as a 'King', is associated with light, and defined as 'mighty'. His works are described as ones where he 'adorns, avenges, blesses, chooses (?) gives.'
Costobarus I, whose name meant "Qōs is mighty" was a native Idumean descended from a priestly family attached to this cult. After Herod, had placed him in command over (στρατηγὀς) Idumea, Costobarus, supported by Cleopatra, eventually tried to prise the kingdom from Herod's Judea. In order to garner local support for his defection, he revived the old cult of Qōs, perhaps to get Idumea's rural population, still attached to its traditional gods, to back him. The name recurs in the Nabataean language in an inscription at Khirbat al-Tannur.where he is represented flanked by bulls, seated on a throne while wielding in his left hand a multi-pronged thunderbolt, suggestive of a function as a weather god. He is also on an altar in Idumean Mamre.
The deity's name was used as the theophoric element in many Idumean names, including the names of the Edomite kings Qōs-malaku, a tributary of Tiglath-Pileser III and Qōs-gabar a tributary of Esarhaddon.