It is probably not a coincidence that three out of the four sample characters in Celestial Chorus weren't Christian. It's almost as if White Wolf thought that releasing a book about heroic Christian mages would have damaged their counterculture cred. The result is a book that's fairly ambivalent about its subject matter.
It would be dishonest to deny that the Celestial Chorus is Mage's designated "Christian faction," but the book does go out of its way to bring up every example of non-Christian Choristers it can think of. It's not an exclusive club. The Chorus believes in religious tolerance . . . mostly. Some members of the Chorus are inflexible fanatics. The Celestial Chorus encouraged the Inquisition . . . and the Celestial Chorus fell victim to the Inquisition. Because back when it was strong enough to be one of the dominant Traditions, it was big enough to contain both the Cabal of Pure Thought and Gnostic heretics.
In a way, this is as it should be. Christianity is bigger than the niche that Mage set aside for it. Something so central to European philosophy, culture, and history should probably have more of an influence in the European Traditions as a whole. Realistically, the Order of Hermes, the Verbena, and the Cult of Ecstasy should probably be majority Christian as well, instead of recruiting primarily from all these pagans that seem to come from nowhere. But White Wolf had its obsessions. If the setting can support a faction like the Hollow Ones, who only exist to imply that goths really do get it, then it almost makes sense to pigeonhole Christianity into one group out of ten and Islam into a hidden 11th faction that people only occasionally remember.
The weird thing, though is that the Celestial Chorus is more than Christianity. Choristers can be Muslim or Zoroastrian or Jewish. There is a large contingent of Hindu Choristers who resent being so long overlooked. The book even acknowledges that there are varieties of Native American spirituality that fit better with the Chorus than they do with the Dreamspeakers.
On the one hand, this means that an already overburdened Tradition now has even more that it needs to account for. On the other, it's latched on to something significant. Maybe the Celestial Chorus represents a theological tendency that crosses religious boundaries. Not all Christian mages join the Chorus, only those that interpret God through a lens of transcendental pantheism and whose soteriology is flexible enough to incorporate the reincarnation of Avatars and extreme syncretism. So the Chorus is just an assembly of heretics - be they Christian, Hindu, Mayan, or what have you. None of them quite fit in with their native doctrines, but they all believe in The One.
That's where the Celestial Chorus is going to wind up, but it's not quite there yet. It's still got a lot of Christian Identity in its DNA. The remnants of the Cabal of Pure Thought, the ones who stayed behind when the rest defected to the Order of Reason, are still part of the Traditions, so we're not yet at the point when we can say, "um, actually, the Sons of Ether have almost as large a percentage of Christians in their ranks, they just don't believe their powers come from God." We're still at a stage where we have to say "the Celestial Chorus is the Christian splat . . . but they're weird . . . but they're Christian . . . but they're weird."
That's why the one and only Christian among the sample characters was also an inheritor to the Greek sibyls. They wanted a vision of Christianity that would still get the goth kids in trouble with their parents.
Let's see, odds and ends. Before it was Christian, the Celestial Chorus was Mithraic, and one of the last Celestial Choristers to follow Mithras speculated that Jesus was a Mage. And hoo boy, that's not the sort of detail I'd have the guts to use in a game. Though I do admit that as an atheist, it's an idea that intrigues me. Imajica, by Clive Barker, implied something similar and it was such an interesting bit of worldbuilding that I immediately lost interest in the main plot. It's not, as you might think, because I want to take the Christian God down a peg, but rather I like the idea that there's no contradiction between human action and the sacred. I guess, if I'd been born at the right time, I'd have been drawn to Arianism (please, before you write me an angry letter, look it up).
The book actually goes into some depth about this issue, and while it denies that the Chorus directed the creation of the Nicene Creed, it does imply that they used the Council of Nicea as cover to hash out some internal political stuff.
Overall, this feels like the most ambitions Tradition Book yet. White Wolf is getting more confident about this whole publishing business and it shows in things like a more elaborate layout and the framing device where the whole book is supposed to be a compilation of ancient Celestial Chorus documents. It doesn't always work - the need to advance the fiction eats up a lot of wordcount that could otherwise have gone to describing the Celestial Chorus - but it works more often than not. Sons of Ether is still my favorite Tradition Book so far, but I definitely feel like we're creeping up on White Wolf's golden age.
Ukss Contribution: There's a subgroup within the Chorus called the Sisters of Gabrielle that's an all-female order of demon hunters. They're pretty badass, but it's unclear why their group is only open to women. Since the art of Gabrielle looks a little like Kassandra from Assassin's Creed: Odyssey, I'm choosing to believe that the Gabriellites are all lesbians.
So that's what Ukss is getting - kick-ass lesbian demon hunters. (But not lesbian stripper ninjas - I promise to keep the male gaze to a minimum).