Orcs are in general very pious and pretty much all of them follow the deities of the Orcish pantheon. Although all gods of all kinds are given respect (They are immenesly powerful, after all, and orcs admire that.), this does not extend to the servants or temples of other deities. Thus an orc will happily burn and pillage a temple of a deity other than their own, but will be upset if someone badmouths the god in question. The fact that the orcs have proven their superiority over the vanquished servants of other gods and furthermore brought honour to their own deities is no excuse for being imious.
Gruumsh: The chief orc god. All other orc gods serve him.
Luthic: The sole female orc deity. Only females may worship her.
Ilneval: The orc deity of strategy and tactics.
Baghtru: The god of brute force and savage might.
Shargaas: The clever and stealthy one.
Yurtrus: The god of plagues.