Islam in Brunei
Islam is Brunei's official religion, 82.70 percent of the population is Muslim, mostly Sunnis of Malay origin who follow the Shafi'i school of jurisprudence. Most of the other Muslim groups are Malay Kedayans (converts from indigenous tribal groups), local Chinese and Dayak Iban converts. Islam was introduced to Brunei by traders arriving from Persia, Arabia, China and the Indian subcontinent. Therefore, other religions can be practiced freely. History

Islam was adopted in the 15th century when a Muslim-Malay was installed as Sultan. The Sultan traditionally was responsible for upholding Islamic traditions, although the responsibility was usually delegated to appointed officials. Since the 1930s Sultans have used rising oil revenues to provide an extensive social welfare system and promote Islam, including subsidising the Haji, building Masjids, and expanding the Department of Religious Affairs (KHEU). The Islamic religious education in Brunei is well organized and structured. In 1956, on the personal request of Sultan Omar Ali Saifuddien III, the government of Johore sent a Senior Islamic Religious Officer, Tuan Guru Haji Othman Haji Said to Brunei to assist the government of Brunei in establishing a similar Government Islamic Religious School as in Johore. He successfully organized and established the Brunei Government Islamic Religious School throughout all districts in Brunei (1956-1962). The 1st School was established in 1956 at Sekolah Sultan Muhammad Jamalul Alam (SMJA) in Brunei Town. The school adopted the same syllabus from Standard 1 to Standard 6 and used the same books as that of Johore Government Islamic School, running in the afternoon at the same school premises as Brunei Government National schools. After completing Standard 6, the students may choose to undergo a special training class for a year to be trained as a qualified Islamic Religious School. Initially, Islamic teachers from Johore were brought in. The Royal family of Brunei is well-educated in Islam. Similar Islamic education was introduced to all the Royal Families of Sultan Omar Ali Saifuddien, (including the present Sultan Hassanal Bolkiah and his wife Raja Isteri Saleha). Special School for the Royal Family was established in 1957 at Istana Darul Hana and the first Islamic Religious teacher was Cikgu Hajjah Salbiah Haji Shafii (wife of Tuan Guru Haji Othman Haji Said). With the constitution in 1959, Islam became the official religion of the country. On 30 April 2014, Sultan Hassanal Bolkiah announced the implementation and enforcement of the first phase of Syariah Penal Code Law in Brunei starting 1 May 2014. Denominations

Sunni Islam 
The Sunni Islam of the Shafi'i school of thought is the official, legal form in Malaysia, although syncretist Islam with elements of Shamanism is still common in rural areas. Mosques are an ordinary scene throughout the country and azan (call to prayer) from minarets are heard five times a day. Government bodies and banking institutions are closed for two hours every Friday so Muslim workers can conduct Friday prayer in mosques. Since it is compulsory for Muslims to perform a prayer 5 times a day no matter where they are, almost all public places, including shopping malls, hotels, condominiums, usually have allocated spaces called "Surau", for performing the Muslim prayers. In 2017, it was reported that Wahhabism doesn't spreading among Bruneian's elite, and that the traditional Islamic theology currently taught in Government schools is gradually being shifted to a view of theology derived from the Middle East, particularly Saudi Arabia. Shia Islam 
The Brunei government has strict policies against other Islamic sects, including a complete ban on Shia Islam, allegedly to "avoid violence between the two faiths that has sometimes broken out in other parts of the world by promoting only the Sunni faith". Due to decades of the Saudi funding, Shia Islam is openly and freely demonized and Shia Muslims are oppressed in the country, their prayers and gatherings are broken up, state's secret service also engages in Shia forced disappearances. Anti-Shi'ism reaches such an extent that the mainstream media always present Iran in bad light while blindly glorying Saudi Arabia. For example, in 2019 Malaysian police raided multiple private functions commemorating the martyrdom of Husayn ibn Ali at the battle of Karbala, arresting scores of foreign and local Shia Muslims. While the true numbers are not known, the number of Bruneian Shia Muslims is estimated at around 26,600. Other sects 
Muslims who believe Mirza Ghulam Ahmad to be the fulfilment of the Islamic prophecies concerning the return of Jesus, the Ahmadiyya, are also present. There are approximately 500 Ahmadis in the country. But now, the Ahmadi's were illegal spreading to all Brunei citizens. Conversions to Islam 
The number of Bruneian converts to Islam has increased ever since Islam became the official religion of the country in 1954. And by 2004, it was recorded that over 16,000 Bruneians had converted to Islam. From 2009 to 2020, there have been 5,884 individuals who have converted to Islam in Brunei. 