First of all understand what is secularism -- then read below
The idea of secularism in Islam means favoring a modern secular democracy with separation of mosque and state, as opposed to Islam as a political movement. Secularism in the Muslim countries refers to the ideology of promoting the secular as opposed to the religion. It is often used to describe the separation of civil/government matters from religious theocracy. Secularism is often condemned by Muslims who do not feel that religious values should be removed from the public sphere, though "Muslim theologians have long distinguished between matters of din [religion] and dawlah [state]."[1] Secular states had existed in the Muslim world since the Middle Ages.[2] The quest for Secularism has inspired some Muslim scholars who argue that secular government is the best way to observe sharia; "enforcing [sharia] through coercive power of the state negates its religious nature, because Muslims would be observing the law of the state and not freely performing their religious obligation as Muslims," says Abdullahi Ahmed An-Na'im, a professor of law at Emory University and author of a book on the future of sharia. A majority of Muslim countries have a dual system in which the government is secular but Muslims can choose to bring familial and financial disputes to sharia courts. The exact jurisdiction of these courts varies from country to country, but usually includes marriage, divorce, inheritance, and guardianship.[3] However, secularism has acquired negative connotations in some Middle Eastern countries and is often criticized as being linked to anti-religion and colonial intervention.