The center of faith in the Dark Medieval world is the Church of Rome--simply called the Church by most folks. It is the shepherd of souls on Earth, founded by Christ's ministry and message to the faithful, and offering salvation through its sacraments.
The Church is the single most powerful organization in the Dark Medieval world. It has vast wealth and political power granted by the faithful. The Church and its rituals permeate every aspect of Western European life, from baptism to marriage to the last rites, and being deprived of the rites of the Church (and therefore of salvation) is one of the greatest terrors of the medieval mind. Excommunication is a real and powerful threat, and the church wields it as a weapon against nobles who oppose its doctrines.
The Church's language is Latin. The Bible and most Church documents are written in that language, all rituals are performed in Latin. The pope in Rome is the supreme head of the Church, and below him are his cardinal and bishops, as well as many religious orders. Those orders range from the monastic Benedictines to military orders like the Hospitalers and the Templars dedicated to protecting the faith and winning back Holy Land in the Crusades. More recently, a new branch of the Church has begun to form, the Inquisition.

The Inquisition
Heresy is a matter of great concern to many in the Church. The various Cathars, Bogomils and others threaten to dilute and confuse the Word of Christ, and that can only lead to damnation for the flock. The pope and cardinals are thus organizing a coherent response to the problem, a program to neutralize heretics before they can spread further. Historically, the Church has been reactive on this matter--various bishops simply dealing with various accusations of heresy as they came up. Rome is now preparing to seek out heresy on its own, through authority from the pope himself. This is what will soon become known as the Inquisition. As of 1230, the Holy Office of the Inquisition has not yet formed in name, but its Dominican organizers are already operating in the Languedoc under the auspices of the Albigensian Crusade launched against the Cathar heretics.
There are those in the Church, however, who know that heresy is only part of a larger problem. Outright monsters and devils walk the Earth in human form to tempt the faithful and lead them astray. Worse yet, they have even corrupted some withing the Mother Church! So no one is above suspicion, and no one can be entirely trusted. The wiles of the Devil are many, and he is capable of quoting scripture to serve his own ends. Therefore, a secret inquisition has been afoot for decades. A growing number of dedicated holy warriors and priests--said to be acting on papal authority--operate from the shadows, hunting the beasts that lurk among men. Most are well educated, and nearly all have True Faith as their weapons and their shield. Cainites are becoming aware of the dangers posed by these mortals who would turn the hunters into prey.

Knights Templar
Perhaps the greatest military order of the Church is the Poor Knights of Christ and the Holy Temple of Solomon, commonly known as the Knights Templar. They were founded in 1114 and officially recognized by the pope in 1128. The white surcoat with red crusader's cross of the order is well known throughout Europe and the Holy Land, along with their black and white checkered banner, surmounted with a red cross. The Templars are dedicated to winning back the Holy Land from the Muslims, and answer only to the pope.
The Templars have learned a great deal from their time in the Holy Land, and the upper ranks of the order include wizards who practice ancient magic and even commune with spirits. They have collected a considerable body of occult lore, along with a collection of relics and treasures. Their wealth, faith and mystic knowledge makes the Templars a potential threat to Cainites, but fortunately they are solely interested in freeing the Holy Land. They will even deal with the Damned if it serves their goals. In fact, the Templars count a few Cainites among their ranks, a fact that would be of great interest to the Inquisition.

Other Faiths
Christianity is by no means the only faith in the Dark Medieval world, although it by far the most populous. Scattered communities of Jews are found throughout Europe. They are often persecuted by Christian authorities and blamed for all manners of atrocities. Tales of Jews using the blood of Christian babies to make their Passover bread sometimes leads to riots and the lynching of many Jews. For the most part, Jewish communities are insular, although Jews have a reputation as moneylenders and merchants (since the Church considers usury a sin). This only fans the flames of jealousy and mistrust towards the Jews.
Islam is the faith that extends over the Holy Land, particularly in the Arabic Peninsula. Muslims controlled large parts of Iberia until the Reconquista forced them back to only the southern province of Granada, but their influence can still be seen throughout the land. Christian armies clash with Muslims in the Crusades, and it is rumored that orders such as the Knights Templars even learned mythic and occults secrets from the Muslims in the Holy Land.
The old pagan beliefs of Europe are also kept alive in many places. Rural folk often celebrate pagan rites alongside Christian holy days. The Church permits this to a degree, even co-opting pagan festivals and making them Catholic holy days. Few places remain wholly pagan, although Lithuania is still a pagan kingdom and parts of the British Isles maintain old pagan ways and beliefs.
Finally, Rome is not the only center of Christian belief. Various heresies continue to thrive in parts of southern and southeastern Europe, some diverging quite a bit from Rome in their portrayal of Christ. The Orthodox, or Eastern, Church also continues to hold sway over much of Eastern Europe and the former Byzantine Empire. In the Levant, there are likewise Armenian, Antiochan and Coptic Christian churches.


The Dark Ages

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