Islam
Islam is a monothestic religion based on the worship of Allah (Arabic for, simply, "God") as revealed by the teachings 6th Century prophet Mohammed. The writings of Mohammed were collected in the Qu'ran (alternatively spelled Koran) and form the basis of this faith.
Islam means "Submission" (to the will of God). A follower of Islam is called a Muslim, meaning "One who Submits".
In period, Muslims were regarded as the enemies of Christian Europe, and reviled accordingly. European period sources include all sorts of slanders and inaccuracies about Islam, including the accusation that they worshipped a variety of idols and devils. Curiously, one of the most feared Muslims, Saladin, was sometimes compared to the Nine Worthies, an example of chivalric virtue.
One major conflict was the Moorish Invasion of the Spanish penisula. While there was, sometimes, a certain degree of harmony within these occupied communities, the Crusades in the Middle East were a series of vicious wars, primarily against Muslims, to "liberate" the city of Jerusalem and the Holy Land from Muslim control. Between Crusades, the lands of Outremer and the Crusader States held an uneasy peace with their Islamic neighbours.
The conflict between Christian and Muslim was somewhat ironic, because during and between each Crusades Muslim influence on European culture became more and more widespread. One pertinent example is that Europeans use arabic numerals rather than roman numerals for mathematics.
Your SCA Persona is a Muslim
Quite likely if you have a Middle Eastern or North African persona. Contact between Christian Europe and the Muslim Middle East was extensive, owing to the Crusades, the Christian practice of pilgrimage, and trade.