So to quickly sum up parts one and two, Cerebus began essentially without religion, with polytheistic gods mentioned primarily as oaths of surprise, then we discovered that some people had been worshipping since ancient times a god that looked like Cerebus, then "Tarim" became an analog for Christ as Dave Sim decided to turn his book into a forum for wider examination of political, social and religious issues through the satiric twist of his funny-animal-in-a-fantasy-world comic book.
In #13, we meet out first priest, the priest of Theyr. The religion followed by the people of Theyr is not established in any detail, but it certainly seems more like medieval European Christianity than, say, the worship of Zeus or Ganesha.
A couple of interesting notes regarding the later assertion that Cerebus is and always was an orthodox Tarimite:
1) When Cerebus is being "tried," he is accused of "consorting with dark demons, high crimes against natural law, making the crops mouldy, not looking like the rest of us . . . and anything else the Church of Tarim can think of in the course of this trial. . . " Asked how he pleads, Cerebus replies "Cerebus *demands* that you release him or he'll call upon his dark masters to turn you into a flock of pious pink toads." As one of the townspeople notes, it's not a half bad defense, but it doesn't sound like one that a true believer of an established orthodox religion would make when accused of heresy and worse by an official of that same religion. Of course, we already know that if Cerebus is really an orthodox Tarimite, he isn't a particularly faithful one.
2) On the other hand, when Necross insists that "None may enter the dark castle of Necross save that they are evil," the farmer, Despuess, immediately capitulates, claiming to be evil and detailing his horrible crimes (like "I take Tarim's name in vain" and "I shirk my chores"). After Necross blasts Despuess out of existence ("Evil, yes! But also incredibly boring!"), he demands to know if the "barbarian captive" is as evil as his captor -- and Cerebus successfully manages to deflect the question, first wanting to see his interrogator face-to-face, then changing the subject, "So you're Necross the mad?" so that he never actually has to either defy Necross nor claim to be evil.
Not pious, not particularly well-behaved, perhaps even only half-heartedly a believer at all, nonetheless, something keeps Cerebus from saying, "Yeah, sure, I'm evil. I stabbed to death an unconscious foe about a year ago, and once used a woman as a battering ram," which might not exactly impress a mad magician bent on world destruction but certainly would make him less boring than Despuess.
But Cerebus doesn't think of himself as evil -- few of us do. He's occasionally regretful that he's done bad things, but he usually thinks of the bad things he does as being necessary and not part of a pattern of wrongdoing that would actually make him a Bad Guy. After all, we are all the heroes in the movies going on inside our heads.
Of course, this last is true whether or not Cerebus was already thought of by Dave as having been brought up as an orthodox Tarimite.
#13 ends with the priest's "Sacred Amulet of the Living Tarim" being tossed aside by Necross, now inside the big stone Thrunk, with a dismissive "This is what I think of your gold trinket." Tarim does not protect the priest. He is squashed like a bug.
(By the way, the priest's amulet doesn't look quite like the Ankhs we will see later throughout the Church of Tarim, preparing in the background the Egyptian climax down the road, but more like the astrological/alchemical symbol for Mercury, which is basically the symbol for Venus -- very similar to an Ankh but with a circle rather than a pointed oval -- only with Mercury there's a crescent on top, opposite the cross. Here, there's no crescent, but there are horns, and the circular part is kind of triangular. Evidence, I think, that even though the Grand Vision had obviously occurred and he was moving toward the socioeconomic and religious commentary that would come to characterize the series, he hadn't yet worked out all the details of even the overall plot. So maybe it didn't "all come to him in a flash.")
The next priest we see is in #15, and he's a very different sort of fellow, even though they are both "priests of Tarim." We now get closer to Christianity, and in particular Roman Catholicism, with the clear implication that priests are expected to be celibate (Cerebus: "Any chance he'll show up at your festival?" Julius: "Probably not -- it's couples only").
On the other hand, there's a touch of the brimstone televangelist in the two priests we see in this issue (I used to think there was only one, but I'm now convinced they are two different characters). Unlike Catholics, but like Assembly of God (the denomination of most famous televangelists of the period, the Bakkers, Jimmy Swaggert, Oral Roberts), these priests are against partying on principle, against makeup and ornamentation in dress, and in general are very puritanical -- a trait Dave seems to assume is fundamental to religion and religiosity, both back when he rejected it at least partly for that reason and now that he has embraced it.
He is not puritanical in his dealings with others -- while he does seem to look down on people who indulge in various ways he certainly doesn't try to insist that anyone not do so. But in his own life, he has removed himself from many of the things he used to find pleasurable, and believes that he is closer to God because he has done so. This does indeed seem to be something very fundamental to his notion of what it means to be religious, even though there are millions of religious people who find no conflict between worshipping god and going out dancing on Saturday night.
In #17, we see men (and an aardvark) pretending to be priests -- Commander Krull and his scribe, Grimes, are trying to sneak out of Fluroc disguised as priests. Cerebus, himself already in a white robe, confronts them. One problem with this issue is that Cerebus and the T'Gitans are all wearing what seem to be priests' robes in the very beginning -- they are not only close enough to fool Krull and Grimes but are very close to what they are wearing. Cerebus' hood is white and theirs is black -- and the hoods of the two Palnan priests were also black -- but if that's the only difference how could a T'Gitan sentry be so sure that he saw two priests leave the city and how could Krull and Grimes be fooled by Cerebus?
Anyway, with this issue we know for sure that Cerebus knows about the Tarimite religion. He knows more about priests than the T'Gitans, which is no great surprise, but also more than Krull, who may have a barbarian background but has been part of the Palnan empire for many years now and one would expect to be fairly familiar with the culture he's living in.
Of course, these could all be simple mistakes of a young writer who had not yet fully blossomed into his powers. Still, it's quite clear that Cerebus is familiar with Tarimism (would that be the right word) on a pretty intimate level to know off the top of his head, as soon as he heard the sentry say that two priests left the city that morning, that they couldn't really be priests, because "these are the High Holy Days from Midwinter to Concordance Eve . . . no priest is allowed to eat salted nuts, comment on the weather . . . or leave his place of meditation"
(see what I mean about the ellipses? Earlier in this essay, I had to elide and ellipsis, because he had a comment stretched across two word balloons, one of which ended in an ellipsis and the next began with one)
Cerebus' bluff does not in and of itself reveal a knowledge of priestly matters, only of the fact that Krull and his companion were themselves ignorant of them (as evidenced by their using this disguise at this time in the first place).
Out next encounter with religion takes us back to the notion that parts of Estarcion, at least, are indeed still pagan. The T'Gitans worship Stromm, God of Thunder, who happens to be Gudre's own son. The T'Gitans are primitive barbarians and apparently easily manipulated. Still, the idea that the god they worship is a real man who walks among them and is very much not really a god is part of Dave Sim's overall commentary on religion that is continuing through these stories.
In issue #19 we meet Perce, who is a fortune teller and a prostitute and, we later learn, a Cirinist who believes in Mother Terim, who makes her first appearance since #2 on the first page of #20, in a quote from "The New Matriarchy" by Cirin.
From this point, things begin to get really interesting.
(also posted to the Cerebus Yahoo group)