1.  Indonesia CIA Factbook

Religions:

Muslim 86.1%, Protestant 5.7%, Roman Catholic 3%, Hindu 1.8%, other or unspecified 3.4% (2000 census)
Population:

248,645,008 (July 2012 est.)
country comparison to the world: 4

Banda Aceh's Grand Mosque.

2.  Islam in Indonesia
Islam is Indonesia's dominant religion with approximately 88%, over 200 million, of its population identifying as Muslims, making it the most populous Muslim-majority nation in the world.

The Indonesian Central Statistic Bureau (BPS) conducts a census every 10 years. The latest data available, from 2000, drew on 201,241,999 survey responses; the BPS estimated that the census missed 4.6 million persons. The BPS report indicated that 88.22 percent (210 million in 2004) of the population label themselves Muslim, 5.87 percent Protestant, 3.05 percent Catholic, 1.81 percent Hindu, 0.84 percent Buddhist, and 0.2 percent "other," including traditional indigenous religions, other Christian denominations, and Jewish. The country's religious composition remains a politically charged issue, and some Christians, Hindus, and members of other minority faiths argue that the census undercounted non-Muslims.

3.  The threat to 'smiling Islam

Until the late 1980s, Islam made so little noticeable impact on Indonesia's politics that few outsiders were aware that this is in fact the world's largest Muslim country. Seven out of eight Indonesians are Muslims, making their numbers 200 million by the end of 2000, or more than those of all Arab countries combined. A large proportion of Indonesian Muslims adhere to syncretistic beliefs and practices (rituals relating to earth spirits, ancestor spirits, deities from the Hindu pantheon), and reject the formal obligations, such as daily prayer, that stricter Muslims consider essential to Islam. Since Clifford Geertz's classic study of Islam in an East Javanese town in the 1950s, it has become common to refer to these syncretists as abangan and to their stricter brothers as santri.

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