Islam in Indonesia

Islam is the largest religion in Indonesia, with 87.15% of the Indonesian population identifying themselves as Muslims, based on civil registry data in 2025. In terms of population, the country has the world’s largest Muslim population, with an overwhelming 251.25 million people consisting of Sunni and non-denominational Muslims. the Pew Research Center estimates them as comprising ~99% of the country's Muslim population in 2011, with the remaining 1% being Shia, who are concentrated around Jakarta, and about 400,000 Ahmadi as well.

In terms of schools of jurisprudence, based on demographic statistics, 99% of Indonesian Muslims mainly follow the Shafi'i madhhab, smaller numbers follow other schools, and the Salafi movement, although when asked, 56% do not adhere to any specific school. The Sunni orders of Sufism are considered essential. Trends of thought within Islam in Indonesia can be broadly categorized into two orientations: "modernism", which closely adheres to orthodox theology while embracing modern learning, and "traditionalism", which tends to follow the interpretations of local religious leaders and religious teachers at Islamic boarding schools (pesantren). There is also a historically important presence of a syncretic form of Islam known as kebatinan, particularly in Java.

Islam in Indonesia is considered to have gradually spread through merchant activities by Arab Muslim traders, adoption by local rulers, and the influence of Sufism since the 12th or the 13th century. During the late colonial era, it was adopted as a rallying banner against colonialism. A 2023 Pew Research Center report gave 93% of the adult Indonesian population identifying themselves as Muslim.