Christianity
There is only one Christian church in Europe — the Catholic Church. There are other Christian churches, but they are in faraway and exotic places like Ethiopia, and most European Christians don't even know that they exist. Besides, they are heretical.
The Catholic Church is still unified — the Orthodox Church has not yet split from the Pope, and the Protestants do not come into existence until the distant future. Tensions are rising between the Eastern church (which will eventually become the Orthodox Church) and the Western (Roman Catholic) church. They squabble about a number of issues (doctrine, procedure, power-sharing). In less than 50 years, this will come to a head and result in the Great Schism, but, for now, the church is unified, and most could not imagine it any other way.
The Church is the most powerful social construct in Europe, and is on the rise. Christianity is on its way to becoming a global religion.
The church is still developing into the form it eventually adopts. On one hand, there are clergy who break the rules against priests marrying and nuns leaving their cloisters. In western Europe, these are often accepted as the norm. On the other, there is a movement to eliminate all “secular” clergy (the priests we think of today), and remake the church with only monks. The church will eventually take a middle path, but, as of 1007, it is unclear which direction the church will move — toward more secularism or more monasticism.
Most characters in an FW game are likely to be Christian, and it is important to understand how important Christianity is to the medieval mindset. To the modern Christian, church is something done on Sunday mornings — unless you have something better to do. The people of 1007 see religion as the most important aspect of existence. It permeates every part of their lives. There is no “denomination-shopping,” and very little skipping of mass. Weddings and funerals are always religious, never civil, affairs. Baptism and Confirmation are major milestones in a child’s growth. People look to the church as an authority figure — they do not feel free to disagree with its teachings, as members of modern churches do. There are no “alternative lifestyles.” Everyone must toe the church’s line. Most importantly, these people live with a real fear of eternal damnation that people today have trouble understanding. Heaven and hell to them are very real places. The influence of Satan and his demons is everywhere. Invoking the Virgin or the saints is commonplace. People who have that kind of religious fervor today are marginalized as weirdos, but it is very much the norm in 1007.