Islam is a religion.
Islam . الإسلام , [ alʔisˈlaːm ] ) is an Abrahamic monotheistic religion which professes that there is only one and incomparable God ( Allah ) and that Muhammad is the last messenger of God . It is the world 's second-largest religion and the fastest-growing major religion in the world , with over 1.8 billion followers or 24.1 % of the global population , known as Muslims . The Quran ( [ kɔrˈɑːn ] ; القرآن , literally meaning `` the recitation '' ; also romanized Qur ` an or Koran ) is the central religious text of Islam , which Muslims believe to be a revelation from God ( Allah ) .