Islam, followed by more than a billion people today, is the world's fastest growing religion and will soon be the world's largest. The 1.2 billion Muslims make up approximately one quarter of the world's population, and the Muslim population of the United States now outnumbers that of Episcopalians. The most populous Muslim countries are Indonesia, Bangladesh, Pakistan, and India. The number of Muslims in Indonesia alone (175 million) exceeds the combined total in Egypt, Syria, Saudi Arabia, Iraq and Iran, the traditional heartlands of Islam. There are also substantial Muslim populations in Europe and North America, whether converts or immigrants who began arriving in large numbers in the 1950s and 1960s. In keeping with tradition, the two main branches of Islam today are Sunni and Shiite.
Beginning in the 1970s and 1980s Islam remerged as a potent political force, associated with both reform and revolution. Given the large number of adherents, it is no surprise that Muslims incorporate a broad and diverse spectrum of positions in regard to liberalism and democracy. Some are secularists who want to disengage religion from politics. Others are reformers, who reinterpret Islamic traditions in support of elective forms of government. Still there are others who reject democracy entirely.