In the medieval stone lanes of Damascus’s old city, where a scattering of bars sits among churches, mosques and antiques shops, Thursday nights used to be known for parties. Live DJs, shots, crop tops, raves — Syrians may have had no political freedoms during the brutal, repressive rule of Bashar al-Assad, but secular Muslims and non-Muslims in the capital could dress, drink and dance as they pleased.

In rural Idlib, the province where Syria’s new Islamist leaders built a rebel ministate during the civil war before overthrowing Mr. al-Assad and seizing Damascus in December, the strongest drink for sale is coffee. Cafes are banned from playing music. Even hookahs are out.

For years, cosmopolitan Damascenes rarely mixed with the increasingly conservative Syrians from the rest of the country. But now, some of Syrian society’s most religious people have suddenly come to rule over some of its most socially liberal.

The change has energized religious Sunni Muslims in the capital, but shaken secular Syrians and the country’s religious minorities. Though the new government has refrained from imposing hard-and-fast restrictions on social freedoms, the abrupt empowerment of hard-liners and the increasingly conservative atmosphere have made liberals curb their behavior, fearing what may come next.

They worry that the new government led by President Ahmed al-Shara, a former rebel who was previously allied with Al Qaeda and the Islamic State, will impose extreme Islamic rule on the country.

“What are we now? Afghanistan?” said Nivine Torossian, 40, the Christian co-owner of Tiki Bar, a longtime stalwart of the Old Damascus nightlife scene.