Humanity's true religion on Innistrad is the Church of Avacyn. The central figure in the Church is Avacyn herself, an archangel so true and so mighty that she held back the darkness of Innistrad. Until recently, Avacyn's presence was so powerful that faith in her yielded true power for clerics and other faithful: prayers to her could cause evil creatures to turn away, silver weapons blessed by her priests could slay great horrors, and runes marked with her symbol could protect entire villages. The Church's efficacy was real and plain to see—a welcome weapon in a world of monsters.
As the demons amassed power in Innistrad, Avacyn knew she would have to destroy them. One by one she would engage them in battle and defeat them. But each time she did, a new demon would appear shortly thereafter. It soon became apparent that the demons could be killed but would return in a different form, since they were beings created of pure mana. Realizing this, Avacyn decreed that "What cannot be destroyed will be bound," and thus her symbol became a silver collar, which was to be symbolically forged shut around the necks of all demonkind.
A key tenet of the Church of Avacyn concerns the conditions of death. For the citizens of Innistrad, the goal of a good life is not to seek to live forever, but to have a restful "sleep" after death. The Blessed Sleep is an eternity of tranquil oblivion, much preferable to the shame of becoming a tormented spirit, mutilated corpse, or undead abomination, as so often happens on Innistrad. The Blessed Sleep is considered a reward for a virtuous and vigilant life. "May you spend an eternity in the ground" is a common blessing among the people of Innistrad.
Cathars are the soldiers of the Avacynian church. They're educated at the seminary at Thraben Cathedral, where they study religious law and martial warfare. After cathars enter the priesthood, they must select a specialization, or mastery. They receive additional training at either Thraben Cathedral or the Elgaud Grounds in Nephalia. From there, they are assigned to active duty at locations throughout Innistrad.
Each mastery has a captain, and in the absence of Avacyn, the personalities of the captains influenced the cathars under their command. Some cathars aligned with particular flights of angels, which had ramifications in the rank and file. Under pressure to safeguard their provinces, the captains were forced to take measures to increase the strength of their cathars in whatever ways they could. The angels tried to assist them, but the wards had failed, and monsters were running amuck. The cathars saw themselves as the last line of defense.
The riders are Innistrad's elite cavalry. They're trained extensively in the equestrian arts, particularly mounted swordsmanship as well as secondary weapons such as the lance. Most are stationed in the Gavony moorland in a walled compound known as Rider's Lock, near the village of Merwald Downs. The compound includes a large manor where Captain Einolf Brandt lives with his wife and family. Brandt is a loyal, competent leader and an excellent equestrian. When zombies attacked the village of Merwald Downs, he sent his riders to evacuate the entire population and sheltered them in the compound until the menace was wiped out.
Cathars of this mastery are battlefield chaplains with healing and protective magic. They're usually armed when they enter a conflict but aren't on the front lines. In a battle, their primary role is to move among the injured and offer healing. Often, a regiment will include several chaplains who can work together to cast large-scale wards. The chaplains are headquartered in the outskirts of Thraben under the command of Captain Nadila Maas. She doesn't have much experience as a leader and there was great discontent among her ranks during Avacyn's absence.
This is the largest mastery, as it requires no specialized magic. Although they protect other locations besides mausoleums, that is their most common duty. Some also guard walls and key locations in Thraben, such as the cathedral, courts, and trade houses. The head of this mastery is a strict, clever man named Lewenhart. He is one of the first to suspect the existence of the Skirsdag, and his investigations into the demon cult nearly cost him his life.
Keepers of the Pale
Cathars of this mastery are known as Keepers of the Pale, or simply the Pale. They specialize in matters surrounding the Blessed Sleep and geists. All members of this mastery live on the Thraben Cathedral grounds, but the Pale undertake long, solitary pilgrimages that last months, sometimes years. They are the most secretive mastery, and their arcane rituals and clandestine nature cause distrust among the other cathars.
Blessed weapons are an important part of Avacynian magic, and these cathars are trained in the art of weapon making. Certain blessings must be said at certain times during the forging process to make a weapon magically effective against a particular foe. Silversmiths are particularly revered because of the difficulty in imbuing the silver with strong magic, especially anti-lycanthropic magic. This mastery has a presence in both Thraben and Elgaud. Captain Frimar has strong ties with the merchant community in Nephalia and spends most of his time at Elgaud. During Avacyn's absence he became aware of the trade in illegal Helvault silver. He established a special detail to investigate and retrieve all objects made from pilfered silver.
Historically, this mastery was made up of detectives who investigated crimes, both mundane and supernatural. They travelled to remote parishes plagued by unexplained murders. More recently, they were tasked with finding werewolves who attempted to lead normal lives. Their role took a darker turn during Avacyn's absence, when a series of inquisitions occurred in Kessig and the Gavony moors. They not only executed those who had not been proven to be werewolves, but also began "enforcing" church law and punishing heretics in unsanctioned trials without angelic witnesses.
During Avacyn's absence, the incidence of devils increased dramatically, and their antics became increasingly destructive and cruel. A group of rogue duelists broke with their captain and set out on their own to hunt down devils. The leader of this group is a former moor chaplain named Roricus who lost his family to a devil "prank" that burned his village to the ground.
The duelists patrol the port towns of Nephalia streets, especially at night, targeting criminals and the illegal corpse trade. They are also the first responders if vampires or werewolves attack inside the port towns. As experts in bladework, the duelists readily engage vampires and often step in for someone who has been challenged to a duel by a vampire, using formal dueling etiquette. Minna of Selhoff is one of the most famous duelists. An accomplished fighter with many victories to her name, she let her celebrity go to her head and now stages traveling shows in Nephalian towns. The neglect of her duties has made her unpopular among her fellow cathars, particularly because there is a great need for her skills.
The Quiver of Kessig
Parish-blades are cathars stationed in parishes and serve as escorts along roads, and the Quiver of Kessig is a relatively new offshoot of the parish-blades that specializes in archery and long-range defense. Some guard walls, churches, or any place that needs defense against airborne attacks. During Avacyn's absence, Captain Raf Gyel moved many of his cathars to the Gatstaf Grotto with the Flight of Herons. Now they function as scouts and rangers for the angels. They have become practically independent from governance of Thraben Cathedral and the church.