The roots reach back to 1676, when a modest bamboo chapel stood on burial grounds outside Batavia's city walls. Its congregation was the Mardijker people - Christianized former slaves of mixed and indigenous descent who spoke Portuguese as their daily language, a legacy of earlier Portuguese colonial presence in Southeast Asia. The Dutch East India Company's Church Council, the Kerkenraad, found it more practical to provide these Christians with their own Portuguese-language services than to force them into Dutch-language worship. There was pragmatism in this arrangement, but also segregation: the Dutch congregation worshipped at Batavia's Dutch Church, while the Mardijker and indigenous Christians used two 'Portuguese' churches. The Binnenkerk, the Inner Church, served the wealthier Mardijker families. The Buitenkerk, outside the walls, served the rest. By the time the bamboo chapel needed replacing, the congregation had outgrown it.

The design commission went to Ewout Verhagen of Rotterdam, head of Batavia's ambachskwartier - the craft district. His plans were approved on July 11, 1692, during the governorship of Willem van Outhoorn. Funding came from an unlikely source: money originally earmarked for the diaconia of Dutch Formosa, the Company's colony in Taiwan. That colony had been crumbling since Koxinga's siege of Fort Zeelandia in 1662, and by the 1690s, the church funds were effectively orphaned. They were redirected to Batavia, where they paid for a permanent church for a Portuguese-speaking community that was itself beginning to lose its defining language. Wealthy Mardijker families contributed alongside Company officials like the former Governor-General Johannes Camphuys. The first stone was laid on October 19, 1693, by Pieter van Hoorn, likely a young relative of the future Governor-General Joan van Hoorn. Two years later, on October 23, 1695, the church was consecrated twice in a single day - once in Dutch in the morning, once in Portuguese in the afternoon.

Much of the land around Gereja Sion was originally a graveyard, and the churchyard still holds eleven graves in its western grounds. The most notable belongs to Governor-General Hendrick Zwaardecroon, who died in 1728. His gravestone, carved from Coromandel stone with a lavish bronze plaque, seems out of place in what was essentially a public cemetery for the Mardijker community and low-ranking Company employees. A governor-general could have been interred with far greater ceremony, but Zwaardecroon's will specified burial among 'ordinary people.' Adjacent to his grave lies an equally elaborate stone marking the resting place of Ragel Titise and her husband Titis Anthonijse, a wealthy Mardijker couple originally from Bengal. That a former slave family could afford a gravestone matching a governor-general's in craftsmanship tells its own story about the social complexity of colonial Batavia - a society of rigid hierarchies that nonetheless produced occasional, remarkable crossings.

Inside the church, the gravestone of Governor-General Carel Reyniersz and his wife Judith Barra van Amstel carries its own improbable journey. The couple donated the land that became the Binnenkerk but died before its completion - Judith in 1646, Carel in 1653. They were not buried at the Buitenkerk at all. When their gravestone was rediscovered in Surabaya in 1922, authorities decided the Buitenkerk was the appropriate home for it, linking two churches and two centuries through a single piece of carved stone. On the walls, wooden plaques bearing heraldic achievements honor individuals like Barent Ketel tot Hacfort, a Company commander once stationed on India's Coromandel coast. After independence, the church was folded into the Protestant Church in Western Indonesia, and in 1957 received its current official name: GPIB Jemaat Sion. But the colonial designation Portugese Buitenkerk held on in common usage for years afterward, a name clinging to a building long after the language and the walls it referenced had both disappeared.

What makes Gereja Sion remarkable is not its architecture, which is solid but unspectacular - a rectangular structure with a pipe organ donated by the daughter of Reverend John Maurits Moor, interior woodwork crafted in Formosa, and the kind of sturdy proportions that survive tropical heat and colonial upheaval alike. What makes it remarkable is continuity. The church has held services through Dutch colonial rule, Japanese occupation, Indonesian independence, and every political convulsion since. The congregation has shifted from Portuguese-speaking Mardijker families to Indonesian-speaking Jakartans, the liturgy from Portuguese to Malay to Indonesian. The wooden plaque commemorating the 1695 consecration still hangs on the wall. The pipe organ still plays. Outside, Jakarta presses in from every direction - motorbikes, concrete, the relentless tropical energy of a city of eleven million. Inside Gereja Sion, the air is cooler, the light softer, and the scale human. The building asks nothing of visitors except what it has asked for 330 years: come in, sit down, be still.