Islam is a monotheisticreligion originating with the teachings of Muhammad, a 7th-century Arab religious and political figure. The word Islam means "submission," or the total surrender of one's self to God. Islam's adherents are known as Muslims, meaning "one who submits (to God)". There are between 1 billion and 1.8 billion Muslims, making Islam the second-largest religion in the world, after Christianity. Muslims believe that God revealed the Qur'an to Muhammad, God's final prophet, and regard the Qur'an and the Sunnah (the words and deeds of Muhammad) as the fundamental sources of Islam. They do not regard Muhammad as the founder of a new religion, but as the restorer of the original monotheistic faith of Abraham, Moses, Jesus, and other prophets. Islamic tradition holds that Judaism and Christianity distorted the messages of these prophets over time either in interpretation, in text, or both. Adherents are generally required to observe the Five Pillars of Islam, five duties that unite Muslims into a community. In addition to the Five Pillars, Islamic law (Sharia) has developed a tradition of rulings that touch on virtually all aspects of life and society. Almost all Muslims belong to one of two major denominations, the Sunni and Shi'a. The schism developed in the late 7th century following disagreements over the religious and political leadership of the Muslim community. Roughly 85 percent of Muslims are Sunni and 15 percent are Shi'a.