Erithian Catholic Church

Erithian Catholic Church is 50% a autonomous particular church of the Catholic Church and 50% it's militant arm. It commands a significant military presence - which, during the ages, ranged from 'world's hidden superpower capable of conquering entire world at ease' to merely a 'significant power'.
Even in the deepest moment of its century long decline it was still powerful enough to finish the Italian Civil War within few weeks, overpowering remnants of Italian Army and socialists militias in what can only be described as a major curb-stomp battle, with its enemies utterly annihilated with almost no significant resistance. Which instantly elevated it to a notable power of Great War.

Structure

Following its semi-pyrrhic victory during the centuries-long struggle of the Age of Fire ended with Hidden World going on a self-imposed exile. Dozens of pocket dimensions were erected, using most advanced magic possessed by the Church. There, magicians began living their lifes in peace, with the age of great wars finally ending.
Erithian Catholic Church went on an exile together with it. It practically splintered itself, with every major pocket-dimension having their own religious structures (in most cases led by a bishop). There was still a centralized control, with significant 'reserves' of the militant groups of the ECC being focused mostly in and around Italy, close to the center of the Catholic Church as a whole. However, many of the regional churches began subtly drifting away - it was mostly ignored by the Church, due to it having much more pressing problems (like fighting protestantism and, then, secularism in a much more mundane way), which recently turned out to bite the Church back.
Many bishoprics self-demoted themselves to a purely religious organizations, forgetting their militant cause of protecting the mundane world from the predations of uncontrolled magic. It wasn't very difficult to happen, as almost half a millenia went without a single black magician being spotted. Though it made things harder when suddenly thousands of them showed up.
Many erithian Enclaves simply ignored the Church's call to arms, instead remaining loyal to their nations. Others would gladly follow the call, but their military potential eroded over time. At this point, the ECC is composed of a much slimmer number of bishoprics (with various militant orders and faithful magicians inhabiting their enclaves under them), but with their number slowly growing. The lack of centralized overseeing caused a lot of heteredoxies (some of which are suspected of being heresies in disguise) to sprung up, to the woe of a now restored Inquisition.
Said bishoprics respond to patriarch, head of the the Erithian Catholic Church whose enclave near Rome includes archives, headquarters and armories of all militant ECC groups. He, in the same time, responds to popes.

Public Agenda

Public agenda of the ECC can be - jokingly - summed up to 'Secure, Contain, Protect'. It's mission is to make sure that magic - generally a great and very useful power - doesn't end up making the world a horrible place (or blow it up entirely) while simultaneously making sure that whenever it does end up making the world go bad, there will be someone to defend the faithful from that. And all of that while upholding the masquerade and keeping the Hidden World truly hidden.
That's, of course, the militant part of the public agenda: ECC simultaneously does all the things the normal Catholic Church does in a mundane world. Including charity works, making sure as many of its sheep as possible will attain salvation and opposing a variety of radically world-altering philosophies and ideologies that just can't stop showing themselves again whenever they are taken out of the picture.

History

Age of the Cross

Erithian Catholic Church was created in first part of the 1st Century, by St. Ezechiel, an erithian Apostle. It wasn't known by this name back then, but it's job was the same as it's today: convert erithians and make sure they do not destroy the new religion. It's growth was rapid, enough to decisively defeat The Ascending Path's Roman Empire during the War of Hatred (known also as) First Thaumaturgical War (AD 165-180).
Christianity, now a state religion of surviving parts of the Roman Empire, has managed to grow widely, with Ascending Path steadily losing ground among the erithians. It ended up to it's another defeat during the War of Murder (or: Second Thaumaturgical War (AD 520-555)), which ended with Ascending Path essentially decimated and majority of Roman erithian world being Christian. However, the sheer level of decimation of the world led to first historical rewrite (through use of Hishbon Aet, a history-altering relic of St.Ezechiel).
This retconed both First and Second Thaumaturgical War out of existence. Even in the new history, the Church still triumphed, just in less militant way (with stores of artifacts preserved from before the rewrite allowing it to scare The Ascending Path from attacking). What's more, certain smaller changes back in the timeline ended with Roman Empire itself becoming much less tyrannical, generally improving the average quality of life.
It was also a moment when erithians as a whole went partially underground, at least in Europe, creating a basis of the Hidden World.

Age of Fire

After winning the Antiquity, the Erithian Catholic Church didn't stop. Age of Fire was an age of relentless - but, ultimately, much needed - persecutions. After the end of Roman Empire the surviving adherents of The Ascending Path split into two parts. Moderates and radicals. While moderates limited themselves to 'average' types of magics, radicals decided to fight with any measure they had, including black and mind magic.
Moderates quickly ended up allying themselves with ECC againt the radicals - and, before the end of the first millenium, ended up converting and merging with the Church. Radicals in the same time decided to jump off the slippery slope all the way beyond the moral horizon. Not only using horrible magic in their hidden war, but also attempting to achieve Ascendence in an increasingly horrible ways (with their failures - no success was noted to this day - being especially horrible).
At the beginning of the Age of Fire they were still capable of causing major disturbance at least regionally, which led to several wars that weren't fully retconned from existence due to Hishbon Aet being rather costly to use - and the wars themselves 'supressed' by mundane means. Overtime they were forces to rely on playing merely supportive role to mundane anti-Church forces, before finally collapsing entirely. These engagements include:
War of the Round Table - Prolonged war waged on still-pagan part of the British Isles prior to its eventual conversion. Began - it's believed - when a significant group of radicals attempted Ascendence via Elemental Magic to become the Fae. With their Ascendence failed (as in many cases) it resulted in semi-omnicidal monsters that decimated big part of England organizing a rule of absolute terror.
It ended when future St. Merlin - himself a shaman and a minor erithian - brokered alliance between the Erithian Catholic Church and a group of surviving local tribes, lead by local warlord named Arthur. The flood of modern techmaturgical weaponry ended with the Fae decimated and either converted into Prime Elementals or broken and imprisoned.
@St. Rorgon's Crusade - What's the worst that can happen when you raid some small noble household in a primitive backwater of already backwater Frankish Kingdom in search of arcane knowledge, lore and artefacts... and flay his family in the process?
A one-man crusade of righterous vengeance, with a single person wiping out pretty much every militant and agressive Path-adhering erithian in Scandinavia (while becoming a Living Saint in the process) and collapsing one of the strongest remaining Path bastions.[
War of Worms - Another open war on the edge of Church-controlled territory: this time in the east. It's believed that a group of surviving pagans in the area of Poland attempted black-magic type Ascendence... and messed up badly (or succeded horribly right).
A sudden epidemy of brain-devouring worms that could easily take over and completely 'replace' humans (by eating their memories and habits) ended up collapsing the easternmost of Catholic states in what was later on masqueraded as 'pagan reaction'. It ended up after almost two decades of struggle (with country and local religious structures utterly collapsing early on), with all but one of the Worm's hives succesfully destroyed.
Albigensian Crusade - A last-ditch attempt by the radicals to sow subversion and cause internal strife within the Church following the failed attempts to - finally - infiltrate it and possibly takeover. With significant part of the Albigensian doctrine being straight gnosticism, the connection wasn't really that hard to make.
The false doctrine was succesfully eradicated, however in a terribly bad manner. Without a doubt, they were heretics whose idea for society equalled its dissolution. Also without a doubt, they were under influence of the radical erithians (that around that time started being called the 'Forbidden'). However, following mass burnings of heretics it was discovered that due to the Forbidden collapsing manpower overwhelming majority of burned - by an overly zealous crusades - were merely misguided mundane humans.
Northern Crusades - A prolonged series of wars in which Erithian Catholic Church seeked to purge remaining holdout of radical erithians that - after their hold on Poland collapsed following the War of Worms - retreated north. It happened simultaneously to more mundane conquest and christianization of the area in early 12th Century.
War ended with full success and the last significant holdout of radicals succesfully squashed. The only thing that ruined the happiness of victors was the Teutonic Order aquiring their own stash of supernatural artifacts and weapons and begining to play increasingly independent role.
War of Wrath - Also known as Third Thaumaturgical War. The most devastating military conflict in history of Mankind, which was supposedly so terrible that nearly entire knowledge of it was succesfully purged from history - which, supposedly, was the only way for Humanity to be able to live.
Nothing is known about the enemy, it is however believed by the Church at large that it was either real demon incursion or the most spectacularly failed Ascendence in history. Whichever side is real, it's also believed that less than a single million of people was alive at the end of War of Wrath, and the world itself would inevitably collapse if not another historical rewrite.
Teutonic Crusade - Waged in early 15th Century, after Polish and Lithuanian Erithian Catholic Church organizations accused their teutonic cousins of heresy. What followed was a swift military action and succesful subjugation of the offenders that happened simultaneously to the great war between the two countries and the Order.
Significant evidence following the crimes of the teutonic erithians were found, and many of them were burned. With most of their material wealth confiscated, the Teutonic Order began it's long decline (being decisively defeated by Poland and Lithuania didn't help). Unfortunately for the Church, it was going to misfire later on, with the humiliation leading to the Order's transition into secular Prussia and then protestantism.
War of Contempt - Also known as Fourth Thaumaturgical War. With moderates converted (more than four centuries ago) and radicals believed to be wiped out to the last at this point (unknowingly few survivors decided to dig deep and not show up for several more centuries), the only significant threat to the ECC existed in the west.
The 'original' Aztec Empire conquered significant part of America (including entire modern Mexico, big parts of Colombia and southern United States and entire Carribean). And, which was believed to be caused by Yucatan Exclusion Zone (later confirmed by the Hell's Report), went even more evil than in the later alrtered timelined.
What began as Western Crusade or American Crusade ended with a fifty years long period of devastating war, with secrecy of magic world compromised early on. It ended with Church's eventural success, and with Aztec Empire all but destroyed. To preserve the secrecy again, an another historical rewrite happened that made the Empire be more mundanely evil than supernaturally.

Age of Iron

Following it's eventural victory in all of the wars waged in the Age of Iron, the Church has all but collapsed - and quite suddenly. The weakening of its mundane counterpart's influence could be dated back to the Black Death plague (conjured by the Hishbon Aet as side effect of the growing Corruption of the Creation after the War of Wrath). It finally exploded in late 15th Century, as Reformation struck.
It's march led to a partial collapse of Erithian Catholic Church structures and forced it to sign the so called Treaty of Vatican, which happened simultaneously to the Council of Trent. It led to establishment of Enclave systems, with erithians in both Catholicism and Reformation-held countries going underground and separating themselves from the mundane world as much as possible: this allowed the Church to spend much less efforts policing them, and redirect their attention to new threats.
Unfortunately, this allowed a few surviving Forbidden worming their way into Enclaves. With the Church slowly collapsing under the strain of fighting war on multiple fronts (as not only Reformation, but also resurgent Jihad and secularism fought against it), they managed to heavily infiltrate (if not just control) a multitude of Enclaves, paving the way for the Great War.

Demography and Population

The overall number of faithful adherents of the Erithian rite of the Erithian Catholic Church is estimated to be close to 15 000 000 prior to the Great War starting. However, less than seven million lives in Enclaves that decided to submit to the Catholic Church's political authority after it's call to arms, and out of that, only less than a half actually possesses significant military presence.
While the word 'erithian' is used as common description of all inhabitants of the Enclaves, the actual number of active mages is closer to one hundred thousand, thrice more if you count people of absolutely basic level of skills, not considered by the locals as potential combatants.

Territories

Enclaves that remained loyal to the Church were those from Italy (vast majority), Austro-Hungary (majority), Poland (vast majority), Bavaria (majority, now destroyed by the Greater German Republic, Portugal (majority), France (minority), Spain (minority), Balkans (minority). Also Great Britain (about 25%, mostly those whose religious authorities could be described as High Church adherents, though not all of them). The few Enclaves in America mostly try for neutrality.

Military

Besides the small mundane military force of every major Enclave (at best a regiment-size, tasked with uphold the law and so on), Erithian Catholic Church also has access to a significant number of active magicians (the actual number surpassing the Forbidden by far, even if the Forbidden magicians tend to be stronger and more ruthless).
It also assumed direct control (Italy) or semi-direct control (Spain) or de facto but not de iure control (arguably, Portugal) or simply notable influence (Poland, Austro-Hungary) control of several mundane countries, with another one (Mexico) currently in a civil war between ECC-supported Cristeros and the radical socialist government.
And that's pretty much only the basic level, with the former paragraph tasked with defending the Enclaves and running the techmaturgic industry (though more powerful magicians do visit battlefields quite regularly), and the latter giving industrial power, mundane soldiers and growing number of Übers and Combat Sorcerers.
The actual supreme military power of the Erithian Catholic Church lies in several knighthood and monastic orders, that - while being in much worse state than before the Treaty of Vatican - are still a significant military powerhouses. With the recruits flooding them, they keep expanding. The list of them beneath.

Knighthood Orders

Knights of the Round Table - Knights following an example of king Arthur and his knights (that, as all of them knows, were closer to barbarian warlords than knights - but still did the right thing when their world ended). Knights of this Order combine typical powers of knights (power amplification allowing them to combat Übers and resistance to 'simple' damages like average calibre rounds) with St. Merlin's holy elemental magic.
Based mostly on British Isled, this order suffered a schism following the papal's call to arms. Many of the Knights now march in the ranks of the British Empire's army ranks, though their loss of St. Merlin's more advanced holy magic (supplanted by Elemental Magic) does struck a blow to the schismatics' credence. The rest was recalled to Italy to join the Holy League's army.
Knights of the Lion - Knights following an example of St. Leo of Monte Cassino. Disappeared in mysterious circumstances following the Treaty of Vatican, returned recently with their numbers diminished into exactly one knight. Taken back, and with their ranks quickly replenished (to at least a hundred) by accelerated training courses.
Their most notable trait is their extreme resilience. Prior to the introduction of Übers into the war, the only way to even temporarily disable a Lion-knight was a concentrated artillery strike or equally concentrated attention of at least several tanks. And that's for the guys produced by accelerated training: the only surviving 'real' knight is confirmed to receive several salvoes of 450mm battleship cannons during the early Italian Civil War and emerge unscathed. Instead, they lack any sort of ranged combat capabilities and they are known to be about as maneuverable as a continent.
(more to come)

Monastic Orders

Sisterhood of St. Ezechiel - An all-female monastic orders following teachings of St. Ezechiel. While limited in numbers even in its prime, every elder sister is a SIGNIFICANT threat to even the most powerful erithians due to their anti-magic aura (that more than allows a mundane soldiers that normally accompany them to kill even the archmagician of the erithians pitifully easy). Even the novices are absolutely invulnerable to mind magic and most Black Magic.
The power of said magic-supression field is powered directly by the Vows. The more Vows a sister takes - being essentially a physically enforced rules forbidding her something - the greater its power. The few of the highest rank sisters Vowed pretty much everything - essentially putting themselves in self-induced coma, with all their senses permanently severed. Instead, their anti-magic field is enough to banish every supernatural being and change any techmaturgic equipment into useless pile of metal within a radius of many kilometres.
(more to come)

Religion

General Info

Quite obviously, the absolutely dominant religion of Erithian Catholic Church is Erithian rite of Catholicism. It's biggest problem currently is a number of heterodoxical movements inside, though to their defense one has to admit that those that had any actual heretical tendencies has already split following the call to arms.
The remaining groups all adhere to the basic tenets of Catholicism, serving as a basis for erithian catholicism. This part of the doctrine is, after all, unchangeable: the Erithian Church allows to have differing views on anything outside of that, which leads to continuous (and quite furious) debates on source, nature and theological meaning of magic.

Living Saints

General Description

Living Saints are a handful of special saints. Erithian Catholic Church accepts prayers for intercission for any of the 'normal' Catholic Church saints (plus many primarily Eastern Orthodox and even some Anglican saints, though they are a massive minority). However they are also saints that have a unique standing. They are saints that didn't fully pass into the Heaven... but instead, remained at the very edge of it.
They can still interceed for those alive before God himself, but they also have a much more important role. They are Holy Magic equivalent of Ascendants and Prime Elementals. A source of magic. A beings into whose footsteps all aspiring magicians walk. Though, in their cases, it's the virtues, faith and works that are truly important, not prying into the eldritch lore for years.

List of Living Saints

St. Ezechiel - A founder of Erithian Catholic Church. An apostle 'forgotten' (on purpose) by the mainstream mundane Catholic Church. A young but extremely talented erithian who stumbled upon Jesus Christ and soon abandoned his past life to lead the faithful among the erithians. His magic amplifies magic... or supresses (or just negates fully) it. Seen as a patron of magic as a whole and magicians of the faithful.

St. Leo - An italian knight that during the War of Wrath did the right thing. His suicidal last stand - done against absolutely overwhelming odds, with a desperate hope to buy time for at least some people to flee from the incoming army - was a turning point of the war. While the enemy leader tore him apart in seconds, his sacrifice caused the area surrounding the battlefield - already filled with Holy Magic from the past ages - to reach the critical point, and flatten not only the enemy leader, but also his entire army. His magic is all about amplifying defense (to the point of becoming temporarily indestructible) while making retreat... significantly harder. Seen as a patron of warriors, self-sacrifice and last stands.

St. Merlin - A shaman from a pretty wild tribe from the lands that now are England. Originally a minor Ascending Path adherent, he ultimately converted when Fae initiated War of the Round Table. He led humans of England (via a council of tribal warchiefs, later 'remodeled' in stories into Round Table itself) to victory... and then disappeared. He is essentially a source of more 'holy' variant of Elemental Magic, different than the on from the Prime Elementals. He is seen as patron saint of elements and, by extension, science.

St. Agnes the Silent - A lowly nun of common birth, from the sisterhood dedicated to St. Ezechiel. She participated in an expansion of the Erithian Catholic Church through lands of the dukedom (and temporarily even kingdom of Poland) in days prior to War of Worms. She was the only member of her convent to succesfully escape when the Worms seized the monastery. She managed to send a warning to the Church (initiating War proper), but remained behind the enemy lines, acting - despite being mute due to her vows - a leading figure of a desperate attempts to save as many as possible from the terror of the Worms' rule. Her magic is defensive and supporting (some healing, a lot of debuff cleansings). She is seen as saint of compassion and conviction.

St. Francis of Assisi - A saint well-known in the mainstream Catholic Church, who actually wasn't known to be a Living Saint for a long while after his death and canonization. Nobody knows why exactly he become a Living Saint, but it certainly happened. His magic can be considered a holy counterpart to the Dryad's magic and includes magic of nature (especially animals). He is seen as patron of nature and animals.

St. Rorgon - A noble of Frankish Kingdom during the age of viking raids. Dabbled in arcane, presumably into Elemental Magic. After losing his family to a raid (led by an Ascending Path-worshipping shaman searching for occult artifacts and writings) he made a vow to God to end the threat once and for all. He departed into the home lands of the invaders... and began reaping his vengence. Hundreds of erithians were slain - in open combat. As, despite his rampage of revenge Rorgon upholded his vow, never killing erithians that weren't supporting/leading the raids, never touching their families... and fighting fair and honourably. He singlehandedly collapsed entire Path structures in Scandinavia, continuously slaughtering shamans for almost two hundred years (he is believed to be slain several times, but each time he returned), kept alive by God according to the vow. His magic is purely combat (and offensive as well) one. He is seen as patron of justice, just wars, warriors, soldiers and crusaders.

XXX - Saint of Freedom, Liberation and, also, of countries and rulers.

XXX - Saint of Knowledge, Pathfinding and Mysteries.

Mythology & Lore

There is no 'mythology', there are only religious dogmas of Catholicism with several half-mythological theories regarding the origin of magic. Most of them contradict each other. Since there is no defined dogma (deciding it would be counterproductive when nobody is really sure about what's the right answer), it is allowed.
Those theories include:
a) 'God just made it with the world'
b) Satan made it to infest the world and made it worse, but due to God still being the true ruler and owner and so on it also got netural and good parts (it's just black magic that's intrinsically evil).
c) Mythical Erithia is, in fact, Garden of Eden, with first erithians discovering the place where humans were cast to from Eden and managed to make/exploit a minuscule hole left by Adam and Eve, to take in power seeping from it and use it for magic.
d) Humans existed in the world prior to Adam and Eve being made/casted out of Eden, with the exiles learning to cultivate the small shards of greatness left in them and spreading this knowledge to other people.

Type

Religious, Organised Religion