Islam is the second largest religion in the world after Christianity, with about 1.8 billion Muslims worldwide. Scholars typically date the creation of Islam to the 7th century, making it the youngest of the major world religions. Born in Mecca, in western Arabia, Muhammad (ca. 570–632), last in the line of Judeo-Christian prophets, received his first revelation in 610. Muslims believe that the word of God was revealed to him by the archangel Gabriel in Arabic, who said, “Recite in the name of thy Lord …” (Sura 96). These revelations were subsequently collected and codified as the Qur’an (literally “recitation” in Arabic), the Muslim holy book. Although Muslims are mostly of one of two denominations; Sunni (75–90%) and Shia (10–20%), there are more denominations in Islam. Generally speaking, Sunni Islam is the majority form of Islam world-wide. Differences between Sunni and Shia are initially about the succession from the Prophet. The Sunni believe that Abu Bakr was rightly chosen as the first Caliph of Islam. Shia Muslims believe that, similar to the appointment of prophets, Imams after Muhammad are chosen by Allah. According to Shia Muslims, Ali ibn Abu Talib was chosen by Allah and thus appointed by Muhammad to be the direct successor and leader of the Muslim community. Ali and ten subsequent Imams were all killed, but the twelfth disappeared and is expected to reappear in the last days as the Mahdi and alongside him there will be Prophet Jesus who returns too. Alawi is the more mystical, minority departure of Shia Islam, and Sufi Islam is a strain of belief and practice that might be found in both Sunni and Shia. It is more mystical and concerned with a personal relationship with the almighty. Wahabi Islam is not a separate denomination but a strain of teaching that arose in the 18th century in Saudi Arabia. (from Sunni Islam) Wahabism adopts a much more hardline interpretation of the Qur’an and Hadith.