Islam
When you arrive in Java, you'll immediately be struck by the omnipresence of Islam in every aspect of social life. Indeed, Indonesia is the world's largest Muslim country in terms of believers. Of its population of around 274 million, almost 90% are Muslims, representing approximately 13% of Muslims worldwide. Every year, 221,000 Indonesians make the pilgrimage to Mecca. The country has some 750,000 mosques.
The evolution of Islam in Indonesia has been relatively peaceful, with no major conquests or clashes with Judaism. On the contrary, the religion had to harmonize with local animist beliefs and the predominant religions of the former Indianized kingdoms, mainly Buddhism and Hinduism. Before the arrival of Sunni Muslim and Sufi traders from South Asia, southern China and the Middle East in the 13th century, Indonesia was largely influenced by these two religions. A fascinating fact to note is that the very first mention of a Muslim community in Indonesia dates back to around 1297, when Marco Polo observed and reported the existence of Muslim merchants living among the Hindu population in Perlak. The merchants, seeking to facilitate trade through a common religion that allowed them to share meals and prayers, were among the first to embrace Islam. By the early 16th century, almost all the rulers of Java had converted. Only Bali, to the east of Java, retained its Hindu kingship and caste system. The religion of Mohammed came later to Java than to Sumatra; indeed, the very Muslim Acehnese still pride themselves on having been the first converts to Islam. In Aceh, Sharia law has been established. In Java, Islam was smoothly integrated into local customs, forming the "Java religion" of Abangan believers, a blend of Islam and age-old traditions. The practice of selamatan, the ceremonial meal, is still common. It celebrates the events of collective life: weddings, circumcision, etc. Every selamatan consists of mountains of rice, which become the symbols of the ritual meal. Today, however, modernist, Middle Eastern-inspired Islam is gaining strength, and Abangans are being encouraged to turn to the "true" faith. Indonesia has long been seen as an example of religious harmony, a symbol of open, tolerant Islam.
Islamic holidays such as Eid al-Fitr (or Lebaran) and Eid al-Adha are celebrated with great enthusiasm in Indonesia. Marking the end of the holy month of Ramadan, Eid al-Fitr is one of the country's most important religious holidays. It's a time for family reunions, forgiveness and the renewal of social ties. Eid al-Adha commemorates Abraham's willingness to sacrifice his son in obedience to God, and is generally followed by the sacrifice of animals such as sheep, goats or cows, some of whose meat is distributed to the poor.
The radicalism of some took root in the 1980s, with the opening of extremist Koranic schools where new Jihad fighters were trained; the best known is the Ngruki pondok, near Solo. But the vast majority of Indonesians practice their religion in a rather moderate way. Islam is also expressed politically through two parties: the Nahdlatul Ulama (NU), which defends traditional Java Islam, and the Muhammadiyah, a reformist organization. Both organizations are relatively moderate and play an active role in national politics.
Hinduism
The introduction of Hinduism to Indonesia dates back to the 2nd century, when merchants and scholars from southern India began to establish commercial contacts with the local populations of the archipelago. This process took place gradually, allowing the Hindu religion to intermingle subtly with indigenous animistic and shamanistic practices. Among the most influential ancient kingdoms were Kutai in East Kalimantan, Tarumanagara in West Java, and Holing (Kalingga) in Central Java. However, it is the kingdom of Mataram that stands out the most, renowned for having built the Prambanan temple, considered one of the most majestic and vast Hindu complexes in the world.
However, the arrival of Islam in the 13th and 14th centuries, followed by its gradual adoption by the elite, led to a decline in Hindu influence in many areas. In response, Bali became a refuge for Hindus fleeing the Muslim areas of Java. Here, Hinduism not only survived, but thrived, becoming the island's predominant religious and cultural pillar. Today, Bali remains a strong Hindu enclave in Indonesia. Hinduism is the main faith of almost 90% of the Balinese population, although it is only practiced by around 2% of the national population.
Important religious events in Indonesian Hinduism include Nyepi, the Day of Silence celebrated as the Balinese New Year (March 11 in 2024; March 31 in 2025). This is a day of reflection during which the inhabitants abstain from all physical and mental activity. There's also Galungan, celebrating the victory of good over evil, and Kuningan, marking the end of the Galungan period (February 28 to March 9 in 2024; April 23 to May 3 in 2025). As for must-visit Hindu temples, Bali's Pura Besakih, known as the "Mother Temple", is a 2,000-year-old relic on the slopes of Mount Agung. Tanah Lot, another of Bali's iconic temples, is famous for its unique location on a secluded rock in the sea. And, as mentioned above, the Prambanan complex, dedicated to the Hindu trimurti deities Brahma, Vishnu and Shiva, is renowned for its intricately detailed carvings and grandiose architecture.
Buddhism
Also originating in India, Buddhism arrived in Indonesia a few hundred years after Hinduism. It enjoyed its golden age under the Sriwijaya dynasty (located in southern Sumatra), between the 12th and 14th centuries, during which time the kingdom was recognized as the greatest bastion of Buddhism in Southeast Asia. Thanks to the wealth acquired through trade, Sriwijaya's rulers were able to create armies to conquer neighboring islands, extending their religious influence as far as Java, and even as far south as Thailand and Cambodia. However, this influence gradually waned with the emergence and expansion of Islam in the 13th and 14thcenturies . Indonesian Buddhists represent around 1% of the population, or almost 2 million people. It includes followers of the three main branches of Buddhism: Theravada, Mahayana and Vajrayana, the majority of whom are of Chinese origin, mainly concentrated in Jakarta, Central Java, the Riau Islands, Banten, South Sumatra and West Kalimantan. The most important religious event is the celebration of Wesak. This emblematic festival, coinciding with the full moon of the month of Wesak (May 23, 2024; May 13, 2025) commemorates the three major events in the life of Siddhartha Gautama: his birth, his death, and his awakening, or enlightenment, transforming him into Buddha. On this occasion, thousands of worshippers gather at Borobudur temple, a 9th-century architectural marvel in central Java, listed as a UNESCO World Heritage Site. This site, the largest Buddhist edifice on the planet, is transformed into a place of spiritual convergence, where chanting and meditation mingle in a spellbinding atmosphere.
Catholicism and Protestantism
Catholicism was mainly introduced by the Spanish and Portuguese, Protestantism by the Dutch. Christians(orang kristen) make up 8% of the population. Two-thirds are Protestant and one-third Catholic. Pope John Paul II visited Flores in 1989. The Chinese have largely converted to Christianity. Churches are found mainly among the Bataks of Sumatra, the Torajas and Minahasans of Sulawesi, the Moluccas, New Guinea, Flores, Timor and Nusa Tenggara. You can also visit Jakarta's Gothic cathedral, a former Dutch building that stands right next to the great Istiqlal mosque.
Confucianism
Confucianism has been present on the archipelago for centuries. Every major Indonesian city has a Chinatown and a strong Chinese community. The Sino-Indonesian community represents nearly 6% of the population. Long classified as a Buddhist organization, Confucianism has only recently gained a place alongside the five major religions. Confucianism became an official religion on January 17, 2000, in a gesture of recognition of Chinese culture. It had previously been banned by decree under President Soeharto. In 2012, the city of Medan hosted the World Congress of Confucianism, but this was disrupted by fundamentalist Muslim groups. Chinese New Year is celebrated in Indonesia, but discreetly.
