In Medieval times religion went through various transitions. Spain had an uneasy truce between the Muslims of Moorish Spain, and the staunch Catholicism of northern Spain. The Christian church experienced its first great schism, with the emergence of the Orthodox church, and a series of heretical off-shoots of the Catholic church. It was a time of conflicting faiths, violent clashes, and the forming of secret socities to escape from open persecution.
Christianity provided the basis for a first European "identity," Christendom, unified until the separation of Orthodox Churches from the Catholic Church in the Great Schism of 1054. Thus started an “Eastern Church” (Orthodox) and a “Western Church” (Catholic). Christianity would see further splits as “heretical” bands appeared, gained popularity, and then were hunted by the Papacy. Some of these split-offs included Catharism (also known as Albigensians), Arianism, Manichaeism, Bogomils, and other various Gnostic off-shoots. They suffered persecution from the Papacy, as did any Jewish believers in Europe.
Arianism found the ire of the Papal Church because of their beliefs that Jesus was not eternal, but inferior to God the Father, and the obvious disbelief in the trinity, which to this day is still a mainframe of Catholic theology. This was a form that took more root in the east than the west, though after the influence wore off in the east, it still remained much longer with the German tribes, who received Arianism’s most successful missionary.
Catharism was a large heretical sect that first appeared sometime in the middle of the tenth century. They lasted despite the persecution, as they were still around in 1181, when they received the name Albigensians, based on the town of Albi, which is a little odd since the center of Catharism was at Toulouse, France. They believed that every human had a spark of divinity, but it was corrupted by the material world. This was a distinct feature of classic Gnosticism, Manichaeism, and Bogomilism. They believed the world was created by a lesser deity, which was corrupt. The goal was freedom from this corruption, which was connected with material existence and could only be achieved by swearing off those things that held people in material bondage. The most dedicated, those who became “Perfecti” gave up all earthly goods, sex, violence, and meat (other than fish) and any foods that resulted from sexual acts, such as eggs. They then depended on charity and alms to eat, and followed the example of Christ and his apostles. Their obvious piety versus the incredible corruption of the Medieval Catholic church was a major reason why it was so hard to stamp out.
Eventually these off-shoots would fade before the end of Medieval times, though the Orthodox church would remain strong, and eventually the Reformation would lead to a permanent split. The faiths of the Medieval ages, heretic and pagan, have faded away, and even the faiths of the same names today are but a shadow of what they once were.