Yet in his sermon, Adi Hidayat claimed to know better than most mainstream historians.

“His name wasn’t Thomas Matulessy but Ahmad Lussy. He was a freedom fighter and a Muslim cleric,” the conservative preacher told his audience.

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Hidayat’s attempt to rewrite Indonesian history split the country’s social media users, with some making light of the preacher’s sermon while others branded anyone who disagrees with him an “Islamophobe”.

Jakarta-based “Arie” responded to the video with sarcasm, writing on Facebook: “Jackie Chan is in fact an Indonesian Chinese Muslim by the name of Zakaria Chaniago. Please don’t tell Adi Hidayat or we’ll never hear the end of it.”

Manggaguru Sitompul from Medan in North Sumatra, meanwhile, wrote that “the polemics over Pattimura’s religion have been used as propaganda against Muslims”, adding that critics had latched on to the debate “to accuse us of being hoaxers”.

Hidayat’s claim was based on the writings of revisionist historian Ahmad Mansur Suryanegara, who wrote in his 2009 book Api Sejarah (The Flame of History) that Pattimura was Muslim.

Yet this assertion has been challenged by both academics and Pattimura’s own descendants.

Tiar Anwar Bachtiar of Padjadjaran University in West Java said Suryanegara had used “unreliable and incomplete sources to make his claims” about the iconic freedom fighter, adding about the assertion Pattimura was a Muslim: “To the trained eye, it was very haphazard.”

Thomas Matulessy, who described himself as “sixth-generation descendant” of his predecessor and namesake, was similarly dismissive of the “hoax”.

Pattimura’s parents were protestant Christians called Corneles and Petrosina Noya, Matulessy said, adding “all this has been borne out by church records, such as the baptism, as well as Dutch colonial records.”

Alternative histories, manipulated textbooks

Revisionist claims and “buried” histories have become increasingly popular in the world’s largest Muslim-majority country in recent years.

Herman Sinung Janutama’s book Majapahit Kerajaan Islam (Majapahit, the Islamic Kingdom), released in 2014, including the claims that the Javanese Hindu-Buddhist kingdom was in fact an Islamic sultanate and that its famed 14th century leader Gadjah Mada was actually a Muslim called Gaj Ahmada.

Wayan Jarrah Sastrawan, a historian and research fellow at The French School of the Far East in Paris, said the dominant religion of the Majapahit empire had been well-documented.

“All of the Majapahit-era inscriptions, which date from 1294 to 1486 and deal directly in religious matters, indicate that the royal court patronised both Hinduism and Buddhism, as well as a network of rural ascetics called resi, but definitely not Islam,” he said.

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The Majapahit empire has become a favourite target of revisionist historians because of the special place it occupies in the narrative of Indonesian nationalism, Sastrawan said.

“The generation of politicians who led the country’s independence movements wanted to find a historical basis for a united Indonesian nation,” he said. “They turned to the premodern past to find powerful states that they could claim to be precursors of modern Indonesia.”

Majapahit fitted the bill because of its size and scope, as the empire’s influence once spanned across Southeast Asia.

“Since then national history textbooks have asserted that the territorial extent of the Majapahit empire closely matched Indonesia’s modern borders, an incorrect claim that is based on a deliberate misreading of a Majapahit-era poem called Desawarnana,” Sastrawan said.

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He said the manipulation of history education to serve political agendas had produced younger generations who were largely sceptical of the “official” version of Indonesia’s history, making them susceptible to conspiracy theories.

Revisionism has even started to gain traction among mainstream Indonesian scholars, according to University of Sydney historian and author of A History of Modern Indonesia, Adrian Vickers.

In a recent essay for the Journal of Global Strategic Studies, Vickers cited the example of two political societies set up in early 20th century Indonesia: the secular Boedi Oetomo (Noble Endeavour), which was founded in 1908, and Sarekat Islam (Islamic Association) formed in 1912.

“The dating of when these two organisations were set up is supported by multiple accounts,” he said. “But a new generation of Indonesian postgraduate students have apparently reversed the order, claiming that Sarekat Islam came first in 1905.”

Vickers said it was “clear that the supervisors of these students had no qualms about letting these alternative dates pass as history”, and suggested that the roots of such revisionism could be traced back to the anti-Islam historical narrative propagated during the Suharto era from 1968 to 1998.

“Suharto’s rule was based on a vision of Javanism, and in this vision, Islam played little part,” Vickers said. “It has led to an unfortunate backlash against Javanism, which explains why Boedi Oetomo was viewed negatively by some Muslim groups.”

The marginalisation of Islamic identity during the Suharto years, he added, had created a “majority with a minority mentality”.

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For Sastrawan, however, Indonesian experts’ vigorous rebuttals of revisionists’ historical hoaxes offered an opportunity for growth and learning.

“As Indonesians become used to seeing conspiracy histories get publicly debunked, they will pick up the critical historical skills that their school education does not offer,” he said.