Islam is the dominant religion in Egypt, with approximately 90.3% of Egyptians identifying as Muslims. The majority of Egyptian Muslims are adherents of Sunni Islam, while a small minority adhere to Shia Islam. Since 1980, Islam has served as Egypt's state religion. Due to the lack of a religious census, owing to the alleged undercounting of non-Muslim minorities in Egyptian censuses, the actual percentage of Muslims is unknown; the percentage of Egyptian Christians, who are the second-largest religious group in the country, is estimated to be between 5% and 15% of the population. Prior to the French campaign in Egypt and Syria under Napoleon Bonaparte, almost all of Egypt's educational, legal, public health, and social welfare issues were in the hands of religious functionaries. Under the Ottoman Empire, the public and political roles of the (i.e., Muslim religious scholars) were reinforced, in an effective continuation of the policies of the Mamluk Sultanate. Traditionally, political divisions in the country were based on religious divisions. During the 19th and 20th centuries, successive governments made extensive efforts to limit the role of the in public life, and religious institutions were increasingly brought under closer levels of state control. After the Egyptian Revolution of 1952, the new government assumed responsibility for appointing officials to mosques and Islamic schools. Likewise, it mandated the reform of Al-Azhar University, beginning in 1961. These policies permitted department heads to be drawn from outside the ranks of the traditionally-trained orthodox . History Arab caliphate In the 7th century, Egypt was invaded and conquered by the Islamic caliphate by the Muslim Arabs. When they defeated the armies of Byzantine Empire in Egypt, the Arabs brought Islam to the country. In 639 an army of some 4,000 men were sent to Egypt by the second Rashidun caliph, Umar, under the command of Amr ibn al-As. This army was joined by another 5,000 men in 640 and defeated a Byzantine army at the battle of Heliopolis. Amr next proceeded in the direction of Alexandria, which was surrendered to him by a treaty signed on 8 November 641. Alexandria was regained for the Byzantine Empire in 645 but was retaken by Amr in 646. In 654 an invasion fleet sent by Constans II was repulsed. From that time no serious effort was made by the Byzantines to regain possession of the country. The Arabs founded the capital of Egypt called Fustat, which was