Most Erfworlders believe in the Titans as Erf's creators or demiurges. Their divine will is used by Ansom, seeking to justify the traditional ruling systems of Erf, and by Stanley, who claims that the Titans have special plans for him that supersede the "mandate" of the royals, as evidenced by his attunement to the Arkenhammer. Images of the Titans are featured in the architecture of many cities; similarly, it would appear that some of the books popped along with cities make mention of the Titans.Erf-b1-p068
Some Erfworlders believe in an a City of Heroes, afterlife in which heroic deeds in combat are especially rewarded.
While no other deities have been mentioned, the Woodsy Elf warlord Tarfu invokes the blessings or guidance of "wood spirits" over troops before sending them into battle.Erf-b1-p057 This would suggest some animistic traits in the beliefs of this Elf brand.
Vinny also notes in First Intermission 37 that Signamancers subscribe to an esoteric philosophy which holds that all Stuff is Foolamancy, or, in Real World terms, that the physical world is an illusion, simply a set of Signs that represent an objects true nature. It is not clear whether this is truly a religious belief, a belief attached to the Signamancer's magical discipline, or simply a philosophical point of view.
A unit's religious beliefs are present when it is popped, though it may become more or less faithful depending on its experience.
Religious debates in Erfworld seem to take the form of the specific "plans" the Titans may have had for Erf and themselves: in other words, Fate. Indeed, talking about fate and destiny is likened to quoting scripture.