Judaism
As is the case with Islam, Judaism is not a major focus of FW. A player wishing to play a Jewish character will find relatively few rules governing how.
Jews in Christendom have it rough, but not as rough as they will later in the middle ages. The church teaches that they must be allowed to live, so that they can achieve salvation by conversion. But, in order to encourage conversion, their lives are kept unpleasant. They are barred from land ownership and most professions — including agriculture. They are more-or-less confined to the cities, entirely dependent on Christians. Most of them work in professions in which they are only allowed other Jews as customers. The poorer of them work as servants. Already, Jews dominate the monelylending business in Europe, simply because they have few other options. Their position as the universal creditor doesn't help their reputation.
Many people in Europe believe that the Jews are responsible for the murder of Christ. The Church officially denies this position. As tensions between the Christian and Islamic worlds rise, Christian hooligans increasingly wonder why nothing is being done about the “infidel at home” first, so pogroms are becoming frequent.
However, the antisemitism in Europe isn't as bad as it will be in the high middle ages. There are not yet widespread laws specifying that Jews must wear distinctive clothes. The first accusations of blood libel (i.e., that Jews must sacrifice gentile children to their god) have probably not yet appeared. The Church, at this time, actively works against antisemitic violence in most places. In some parts of Christendom, such as southern France, Jews have it just about as good as any Christian.
Jews in the Islamic world have it much better. Islam is not currently in an antisemitic phase. Though officially second-class citizens (a legal designation under sharia), Jews in many places (especially Spain), can pursue many careers, and even attain positions of great power.