When Islamic armies conquered Spain during the eighth century, they gave more legal rights to the Jewish population of their new kingdoms. Conquering almost all of the Iberian Peninsula within one hundred years, giving Jews positions of influence and power as advisors and tradesmen. When Christians fully retook the Peninsula in 1492, the Christian Monarchs Ferdinand and Isabella began the Inquisition, which either forced the Jews to convert to Catholicism or flee the country.

The Prophet Muhammad died in 632, having united the entire Arabian peninsula into a single polity under Islam. By 732, Islamic armies had swept across north Africa, conquered the Iberian Peninsula, and were heading into France. At the Battle of Tours, a Christian army under Charles Martel defeated the Islamic army of Abdul Rahman, halting the Islamic advance and making the Muslim armies stop in Spain.

The primary sacred religious text of Islam is called the Quran. The Bible is the primary sacred religious text of Christianity; the Torah the primary sacred religious text of Judaism; and the Vedas the primary sacred religious texts of Hinduism. The Gospels are a part of the Christian New Testament of the Bible that tells of Jesus Christ from various perspectives (most importantly Matthew's, Mark's, Luke's, and John's).

The prophet Muhammad is considered by Muslims to be the last prophet sent by God to mankind in order to restore the true monotheistic religion of Abraham. He unified the region of Arabia under one religion, Islam, and paved the way for the subsequent fifteen hundred years of Islamic history. In the early years of his preaching, Muhammad was mostly condemned by the authorities in Mecca, so he and his followers fled to Medina, where he continued to teach and preach for eight years until he had gained a large enough following to march on the city of Mecca.

In the early part of the fourteenth century, the French King Phillip IV and Pope Boniface VIII clashed over whether or not the clergy should be made to pay taxes to secular authorities without the permission of the Pope. This conflict came to an end when Boniface was captured by French forces and died in the ordeal. To ensure continued papal loyalty, Philip installed a new Pope, Clement V, in the city of Avignon in France. The Papacy would continue to reside in France from 1305 to 1378.

The Concordat of Worms (1122) is generally seen as the end of the first major power struggle between the Papacy and the monarchs of Europe (particularly the Holy Roman Emperor) during the medieval era. Prior to the Concordat, the Emperor and the Papacy had disagreed over who had the right to appoint bishops and other church officials and to whom those officials ultimately owed their loyalty. The Concordat determined that in secular matters, the bishops were loyal to the monarch, but in spiritual matters, were loyal to the Pope. Essentially, bishops now owed allegiance to both the Pope and to the monarch. This is seen as a major turning point in European history—both an important part of the rise of Christianity and a precursor to the emergence of nation states.

John Wycliffe was an English theologian in the fourteenth century who was sharply critical of the Papacy and the abuses of the Catholic clergy. Although Wycliffe died of natural causes, he was posthumously excommunicated, his body dug up and "executed" as a heretic in the fifteenth century, demonstrating the dangers of Wycliffe's writings to the established order of things. Jan Hus was another church reformer, a Czech theologian of the late fourteenth and early fifteenth centuries. He advocated that the Bible should be the guiding force for all Christians and challenged the power of the Papacy. He was executed, a move that sparked the decades long Hussite Rebellion. Both men can be seen as early precursors to the Protestant Reformation that would grip Europe a century later.

The Christian tradition of Scholasticism evolved out of the earlier (and concurrent) tradition of monasticism. It involves marrying Christian ethics and beliefs with an approach to learning focused on reasoning, inference, and questioning. The tradition of Scholasticism grew in prominence in the twelfth and thirteenth centuries, and much of the tradition is based on the writings of the famous Christian philosopher and theologian, St. Thomas Aquinas.

The tradition of paying one-tenth of one's income to the church comes from the Jewish faith, but was widely accepted in Christianity during the Medieval period and continues to be in some parts of the world today. This payment was known as a "tithe," and all men were expected to pay it.

In the feudal system, there were lords (the owners of land and the offerers of protection); vassals (those who fought for the lords in exchange for tracts of land or payment); and serfs (those who worked the land in exchange for protection).