Faction name: New Papal States
Faction name: Purgatorium or some other fancy Latin name.
Leader (Or what his/her title is called): Archabbot Michael. He is elected from a council of Abbots, and Abbess.
Location & Capital: South of France (Gascony, Languedoc, Provence, Dauphiné, Savoy, Auvergne, moving to more hostile North to flee from the Papal influence), Switzerland, Tyrol. Capital is in Avignon at the Papal Palace.
Ideology: The Great War is the Last Judgement. The world has become the purgatory. Each living humans left are souls who have been touched by God's grace, but are still imperfectly purified. It is then the mission of everybody to live a life of prayer, and follow the example of the Christ, so they can go to Heaven. They believe in some sort of reincarnation. They consider the Pope as the Antichrist. The society is built around monastry, who follow various monastic rules (the dominant is the rule of St Benedict). Being a monk, or a nun isn't compulsory, but anybody can join at any age after a period of test, to judge if the person is spiritually ready for joining the monastery. They are pacifists and to some extent anarchists.
They are quite divided on the questions of Ghouls. The actual consensus is that they are horrible sinners that should go straight to Hell, but the fact that they survived show that they have been given a second chance by God. It is advised to the Ghouls to take the vow, and in some case are forced (especially if they are unrepentant), even if they aren't made for monastic life, or refuse to (in which case they are locked in a room, with a guard in front of the door who have to chant prayer all day to purify him). In rare cases, some Ghouls live a secular life, and live more or less accepted among smooth skins farmers, which is quite dangerous as some Christians see them as demon to be slaughtered.
A particular order is the Monastery of Saint Antony (former bishop of Avignon). They are errands monks who consider the whole world to be a monastery, and that everybody is a pilgrim. They made the vow of eternal pilgrimage, and to never stay on the same place for more than a year. They go to remote place to give spiritual guidance, religious ritual, and aid in farm work in exchange of food and shelter, or visit monastery to discuss theology/philosophy/science/history/or whatever they are interested in. Those too old to continue their physical pilgrimage, retire in monastery, or become hermit to continue the spiritual pilgrimage. They are prone to some heresy, but are respected, and generally considered as harmless.
Religion (?): Catholic Schism/Benedictain/Fraticelli
Technology (?): 18th Century Pre-Industrial, with some pre-war tech mainly used for crafting farming and construction tools.
Currency (?): No currency. Collectivist society, view money as a mark of the devil. Mainly an agricultural economy built around self-sufficient Abbeys, which help each other in time of need, or for large scale project, like irrigation, dykes, or large furnace, that need a lot of manpower, resources, and skilled specialized workers. The society is principally rural.
How nation was started, etc: It started as the Ecumenical Council of Rome in AD 2256-2257. The clergy of Southern France who went to Rome were horrified by the corruption of the Roman Church. The bishop Antony of Avignon decided to leave Rome in the middle of the Council, and went back to his diocese. Being a prominent spiritual leader in Provence, many of the Southern French clergy followed him, and hold an Ecumenical Council at Avignon from January to June in AD 2257. Bishop Antony was elected as Anti-pope, the Pope of Rome was excommunicated, all the clergy faithful to the Roman Church, all the bishopric in Provence were all disbanded to be replaced by abbey. 2 years later the bishop Antony abdicated and formed an order of errands monks. He died in 2268, was beatified and canonize the following year, his errands monks order then took the name of Monastery of Saint Antony. They quickly spread their faith outside of the Italian peninsula from the Alps to the Atlantic.
.Military power: 2.25 million soldiers
People: 5.5 million.
Is it even possible to have 2.25 million soldiers in a post-apocalyptic setting? The only country in our world that have such gigantic number of soldiers is China, and they've got a really large population to support their military. 5.5 million population isn't enough for the industrial and agricultural power necessary for such number of soldier. The population should be about 300-500 millions. Or maybe it isn't a standing army, and follow the model of peasant-soldiers like the Han or Romans (the number of the army is still too big), where soldiers are posted at the frontier to cultivate (to support themselves to some extent) improve infrastructure, and colonize newly conquered land.