Islam is a monotheist faith which appeared for the first time in the Arabian peninsula during the 7th century. The foundation of its faith are held in their holy text, the Koran. This text contains the revelations of Muhammad, regarded as the last prophet, bringer of law, sent by God. The Islamic religion soon spread from the Arabian peninsula, through the Middle East, and today it is professed by the 23% of the global population. Islam is divided into two main categories: the Sunnite Islam and the Shiite Islam. According to estimates, in the Islamic world Shiites represent 15% of the world’s Muslims population. Unlike the Sunnites, the Shiites confer on the twelve successors of Muhammad the role of “guide”, being charged with this responsibility by the prophet and divine will. Currently, the country with the highest number of Muslims in the world is Indonesia. Islam is the guide religion of the Arabic world.