ONE of Indonesia’s newest brands of beer, Prost, traces its ancestry back to 1948 when Chandra Djojonegoro, a businessman, started selling a “health tonic”, known as Anggur Orang Tua, from the back of a bright-blue lorry at night markets in the coastal city of Semarang. A troupe of dancing dwarves would pull in the punters, while Djojonegoro peddled shots of what was, in essence, a fortified herbal wine to fishermen. It kept them warm during the chilly nights in the Java Sea.

The tonic is still sold in bottles with distinctive labels depicting an old Chinese man with a thick white beard. The company that makes it now produces a vast range of consumer goods, and Prost beer is the latest addition to its range. It is made in a $50m brewery that opened in August 2015, filled with shiny stainless-steel machinery from Germany. Thomas Dosy, chief executive of the subsidiary that produces Prost, says that given Orang Tua’s history in the booze business it was natural for the company to move into Indonesia’s $1bn-a-year beer market.

It will not be straightforward. Conservative Muslim groups have become more assertive. Only months before the brewery opened, the government slapped a ban on the sale of beer at the small shops where most people buy their groceries. It led to a 13% slump in sales, according to Euromonitor, a research firm. The government minister who issued the decree has since been sacked, but his ban remains in place. And Muslim parties in parliament are still not satisfied. They are pushing legislation that would ban the production, distribution and consumption of all alcoholic beverages. Drinkers could face two years in jail.

The law is unlikely to pass. Muslim parties control less than one-third of the legislature’s seats. The government is proposing a far more limited law aimed at curbing the production of toxic home-brews, known as oplosan, which are responsible for nearly all alcohol-related deaths in Indonesia. Turning Indonesia dry would be seen by many people as an affront to the cultural diversity of the sprawling archipelago, which has large Buddhist, Christian and Hindu minorities, as well as many Muslims who are partial to a cool one.

Brewers argue that alcohol is not an import from the decadent West, as the puritans often claim, but has been produced and consumed in Indonesia for at least 700 years. “It is part of the culture of Indonesia,” says Michael Chin, chief executive of Multi Bintang, the country’s biggest brewer. Indonesians consume less than one litre of alcohol per head a year, belying Muslim groups’ claims that booze is creating a health crisis. Still, even without a national prohibition, Islamists will push for local bans—such as the one in force in Aceh since 2005 and adopted elsewhere.

Beyond booze, the state-backed council of clerics, the Indonesian Ulema Council (MUI), has in recent years passed edicts condemning everything from homosexual partnerships to the wearing of Santa hats. Although these have no legal force under Indonesia’s secular constitution, vigilantes have sometimes used the edicts to target revellers as well as religious and sexual minorities. Partly at the MUI’s urging, parliament has passed sweeping anti-pornography laws, which some Indonesians see as a threat to artistic and cultural liberties. Muslim groups are petitioning the courts to interpret the law in a way that would criminalise extramarital sex. They are also making more use of laws against blasphemy—notably in the trial against the governor of Jakarta, Basuki Tjahaja Purnama, a Christian of Chinese descent.

Still, for a country with the world’s largest Muslim population, Indonesia is remarkably permissive. Night spots in Jakarta, the capital, and tourist magnets such as the island of Bali have their raunchy sides. In Semarang, Mr Dosy predicts steady growth in domestic sales of 8-9% per year, buoyed by a growing number of middle-class tipplers. Most Indonesians, proud of their tradition of tolerance, will be hoping that he is right.