Lay investiture refers to the ability of secular rulers to appoint (or “invest”) individuals in church positions. Lay investiture was common in Europe in the ninth, tenth, and eleventh centuries and led to many disputes between secular rules and the church authorities. The situation was partially resolved in 1122 with the Concordat of Worms, which resolved the dispute between the papacy and the Holy Roman Empire over who had the authority to appoint church officials.

During the Middle Ages religious tolerance was generally greater in the Dar al-Islam than it was in Christian Europe. Muslim authorities insisted on political submission of conquered peoples, but they did not (generally) force conquered peoples into conversion. This was in stark contrast to Christian Europe where non-Christians were routinely forced into conversion (most notably the Jewish population of Spain during the Spanish Inquisition).

The Sunni-Shiite division, which divides Muslims to this day, occurred in the mid-seventh century, less than a hundred years after the foundation of Islam. The division occurred as a result of different interpretations over who should hold power in Islam after the death of the Prophet Muhammad.

The Temple of the Sun was the chief place of worship of the Inca people in their capital city of Cusco. The Sun God was the chief deity of the Inca people and the Emperor was meant to be revered as a living descendant (or incarnation) of the Sun God.

According to Islamic belief, Mohammed was praying in the mountains one day, in the early seventh century, when he was visited by the angel Gabriel. Gabriel is believed to have passed on the word of God to Mohammed. It was from this divine incident that the religion of Islam would be formed.

The Dar al-Islam is the name given to everywhere in the world that is under the rule of Islamic law. Dar al-Islam literally means Abode of Islam or Home of Islam, and is contrasted against the Dar al-Harb, Abode of War.

After its formation in the sixth century, Islam spread rapidly around North Africa, Central and Southern Asia, and the Middle East. Islam had reached India by the early seventh century.

Islam was founded by the Prophet Muhammad in the seventh century CE. It is an Abrahamic religion, which means it continues the same monotheistic tradition as Judaism and Christianity. Islam spread extremely rapidly around the Middle East and North Africa in the centuries after its foundation.

The Five Pillars of Islam are: Faith - the belief that Allah is the one God and Muhammad is his Prophet; Prayer - the action of praying five times a day in the direction of Mecca; Charity - giving a portion of one’s wealth to the needy; Fasting - the obligation to abstain from eating food during the daylight hours of the month of Ramadan; Pilgrimage - the duty, if one is able, to make a pilgrimage to Mecca at least once in one’s lifetime.

Jerusalem, which is also a holy city to Jewish and Christian people, is an Islamic holy city because it is believed that the Prophet Mohammed ascended to heaven from Jerusalem. The fact that Jerusalem is a holy city in the three largest monotheistic religions in the world has been a source of constant tension and bloodshed for more than one thousand years.