Islam in Indonesia

is the largest religion in Indonesia, with 87.06% of the Indonesian population identifying themselves as Muslims, based on civil registry data in 2023. In terms of denomination, the overwhelming majority are 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 school, although when asked, 56% do not adhere to any specific school. 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. There is also a historically important presence of a syncretic form of Islam known as kebatinan.
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 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. Today, although Indonesia has an overwhelming Muslim majority, it is not an Islamic state, but constitutionally a secular state whose government officially recognizes six formal religions.

Distribution

Muslims constitute a majority in most regions of Java, Sumatra, West Nusa Tenggara, Sulawesi, coastal areas of Kalimantan, and North Maluku. Muslims form distinct minorities in Papua, Bali, East Nusa Tenggara, parts of North Sumatra, most inland areas of Kalimantan, and North Sulawesi. Together, these non-Muslim areas originally constituted more than one-third of Indonesia prior to the massive transmigration effort sponsored by the Suharto government and recent spontaneous internal migration.
Internal migration has altered the demographic makeup of the country over the past three decades. It has increased the percentage of Muslims in formerly predominantly-Christian eastern parts of the country. By the early 1990s, Christians became a minority for the first time in some areas of the Maluku Islands. While government-sponsored transmigration from the heavily populated Java and Madura to less populated areas contributed to the increase in the Muslim population in the resettlement areas, no evidence suggests that the government intended to create a Muslim majority in Christian areas, and most Muslim migration seemed spontaneous. Regardless of its intent, the economic and political consequences of the transmigration policy contributed to religious conflicts in Maluku, Central Sulawesi, and to a lesser extent, Papua.

Islam in Indonesia by province and region

This is a data table of the percentage of Muslims in Indonesia, provided by the Ministry of Religious Affairs for 2022:

Province	Muslim population	Total population	Muslim percentage
Aceh	5,356,635	5,432,312	'
Bali	434,941	4,304,574
Bangka Belitung Islands	1,344,903	1,490,418
Banten	11,686,756	12,321,660
Bengkulu	2,017,860	2,065,573
Central Java	36,773,442	37,783,666
Central Kalimantan	2,011,763	2,706,950
Central Papua	162,740	1,348,463
Central Sulawesi	2,450,867	3,099,717
East Java	40,179,566	41,311,181
East Kalimantan	3,446,652	3,941,766
East Nusa Tenggara	523,523	5,543,239
Gorontalo	1,191,484	1,215,387
Highland Papua	27,357	1,459,544
Jakarta	9,491,619	11,317,271
Jambi	3,514,415	3,696,044
Lampung	8,598,009	8,947,458
Maluku	997,724	1,893,324
North Kalimantan	533,675	726,989
North Maluku	1,005,727	1,346,267
North Sulawesi	849,253	2,666,821
North Sumatra	10,244,655	15,372,437
Papua	320,442	1,073,354
Riau	5,870,015	6,743,099
Riau Islands	1,671,242	2,133,491
South Kalimantan	4,054,044	4,178,229
South Papua	143,610	522,844
South Sulawesi	8,359,166	9,300,745
South Sumatra	8,508,999	8,755,074
Southeast Sulawesi	2,593,226	2,707,061
Southwest Papua	230,904	604,698
West Java	48,029,215	49,339,490
West Kalimantan	3,320,719	5,497,151
West Nusa Tenggara	5,361,920	5,534,583
West Papua	213,230	559,361
West Sulawesi	1,217,339	1,450,610
West Sumatra	5,528,423	5,664,988
Special Region of Yogyakarta	3,433,129	3,693,834

Region	Muslim population	Total population	Muslim %
Java	149,593,727	155,767,102	'
Kalimantan	13,366,853	17,051,085
Lesser Sunda Islands	6,320,384	15,382,396
Maluku Islands	2,003,451	3,239,591
Sumatra	52,655,156	60,300,894
Sulawesi	16,661,335	20,440,341
Western New Guinea	1,098,283	5,568,264

Denominations

in Indonesia reflect the activity of Islamic doctrines and organizations operating in Indonesia. In terms of denomination, Indonesia is a majority Sunni country with minority of other sects such as Shia Islam and Ahmadiyya. In terms of Islamic schools of jurisprudence, the Shafi'i school is dominant in Indonesia at large. Proliferation of the Shafi’i school is considered to be due to Arab merchants from the southern Arabian Peninsula who followed this school of jurisprudence.

Division of Islam in Indonesia

Classical documentations divide Indonesian Muslims between "nominal" Muslims, or abangan, whose lifestyles are more oriented toward non-Islamic cultures, and "orthodox" Muslims, or santri, who adhere to the Orthodox Islamic norms. Abangan was considered an indigenous blend of native and Hindu-Buddhist beliefs with Islamic practices sometimes also called Javanism, kejawen, agama Jawa, or kebatinan. On Java, santri was not only referred to a person who was consciously and exclusively Muslim, but it also described persons who had removed themselves from the secular world to concentrate on devotional activities in Islamic schools called pesantren—literally "the place of the santri". The terms and precise nature of this differentiation were in dispute throughout the history, and today it is considered obsolete.
In the contemporary era, distinction is often made between "traditionalism" and "modernism". Traditionalism, exemplified by the civil society organization Nahdlatul Ulama, is known as an ardent advocate of Islam Nusantara, a distinctive brand of Islam that has undergone interaction, contextualization, indigenization, interpretation, and vernacularization in line with socio-cultural conditions in Indonesia. Islam Nusantara promotes moderation, compassion, anti-radicalism, inclusiveness, and tolerance. On the other spectrum is modernism, which is heavily inspired by Islamic Modernism, and the civil society organization Muhammadiyah is a known ardent proponent. Modernist Muslims advocate for Islamic reform in Indonesia, which is perceived as having deviated from the historical Islamic orthodoxy. They emphasize the authority of the Qur'an and the Hadiths, and oppose syncretism and taqlid to the ulema. This division, however, also has been considered an oversimplification in recent analysis.

''Kebatinan''

Various other forms and adaptations of Islam are influenced by local cultures that hold different norms and perceptions throughout the archipelago. The principal example is a syncretic form of Islam known as kebatinan, which is an amalgam of animism, Hindu-Buddhist, and Islamic—especially Sufi—beliefs. This loosely organized current of thought and practice was legitimized in the 1945 constitution, and in 1973, when it was recognized as one of the agama, President Suharto counted himself as one of its adherents. The Kebatinan or Kepercayaan has no certain prophet, sacred book, nor distinct religious festivals and rituals; it has more to do with each adherent's internalized transcendental vision and beliefs in their relations with the supreme being. As a result, there is inclusivity in that the kebatinan believer could identify themselves with one of six officially recognized religions, at least in their identity card, and still maintain their kebatinan belief and way of life. Kebatinan is generally characterized as mystical, and some varieties were concerned with spiritual self-control. Although many varieties were circulating in 1992, kebatinan often implies pantheistic worship because it encourages sacrifices and devotions to local and ancestral spirits. These spirits are believed to inhabit natural objects, human beings, artifacts, and grave sites of important wali. Illness and other misfortunes are traced to such spirits. If sacrifices or pilgrimages fail to placate angry deities, the advice of a dukun or healer is sought. Kebatinan, while it connotes a denial of the militant universalism of orthodox Islam, moves toward a more internalized universalism. In this way, kebatinan moves toward eliminating the distinction between the universal and the local, the communal and the individual.