The seemingly harmless event, in which the popular Arab-Israeli journalist Sayed Kashua talked about pluralism and tolerance, broke a long-standing ban on holding activities in public buildings on the Jewish day of rest.
That turned Kiryat Yovel, a tranquil neighbourhood in west Jerusalem, into the latest battleground in Jerusalem's protracted culture war between Jewish conservatism and pluralism.
After years of setbacks, Jerusalem's secular population has begun to push back against what many believe are heavy-handed tactics by the city's ultra-Orthodox residents to impose their religious mores on the general population. A growing number of restaurants now open on Saturday, an array of cultural events have sprouted up, and for the first time in years, a longtime exodus of secular residents for nearby suburbs appears to have halted.
"We're not against the ultra-Orthodox, we're for tolerance and integration and against intimidation. But from no public services offered on Saturdays to promoting gender segregation, the community is undermining the very basis of our democratic state," said Dina Azriel, a leader in the grassroots "Free Kiryat Yovel" initiative, which sponsored the recent lecture.
While most Israelis are secular, Israel's founding fathers gave Judaism a formal place in the country's affairs, and Orthodox rabbis strictly govern religious events such as weddings, divorces, and burials for the Jewish population. The ultra-Orthodox are also perennial kingmakers in Israeli coalition politics, though they make up only about 10 per cent of the country's population.
The influence of the ultra-Orthodox is especially pronounced in Jerusalem, where their numbers are proportionally much larger than the national average. Jerusalem, Israel's largest city, is split almost evenly into thirds between secular and modern Orthodox residents, Muslim Palestinians, and the ultra-Orthodox Jews.
Many modern Orthodox Jews live and work with the secular population while maintaining a religious life style, in contrast to ultra-Orthodox, who choose to live in insulated enclaves.
The ultra-religious have used their large numbers and political muscle to shape modern Jerusalem. The city grinds to a virtual standstill on the Jewish Sabbath, with businesses closed, public transportation halted and few options for entertainment.
Attempts to change this status quo have prompted violent backlashes from the ultra-Orthodox, who haven't hesitated to block roads, clash with police or send tens of thousands of activists into the streets when ordered by their rabbis. In 2009, the city experienced riots when it allowed a parking lot near Jerusalem's Old City to open on the Sabbath to serve out-of-town tourists.
In recent years, the ultra-Orthodox have grown bolder, pressuring the local bus company, Egged, to operate gender-segregated lines through religious neighbourhoods, attempting to separate men and women on public sidewalks and ripping down billboards with female images on them. Because of the threat of vandalism, Egged recently decided to cease all advertising on its Jerusalem buses by October 2013.
The "Free Kiryat Yovel" movement was formed after ultra-Orthodox activists were allowed to build a kindergarten that maintained a wall to separate religious and non-religious preschoolers. It took four years of petitioning the local community centre to win a permit for the Sabbath lecture.
"We're in a really critical time right now, and I'm not optimistic," said Sarit Hashkes, who runs another secular rights group, called "Be Free Israel."
"What we're seeing now is co-operation of state and police officials with the ultra-Orthodox. Women are being pushed aside, and everything is pushed more to the right."
The group is behind a number of initiatives, like offering discount cards to patrons to use at restaurants that are open on the Sabbath to increase "secular buying power."
Hashkes said momentum among the secular population is percolating, but not without an equally fierce backlash. While separate sidewalks are officially banned, she said some streets were still off limits to women during the recent Jewish Sukkot holiday.
Just last week, a prominent female activist was arrested for wearing a traditionally male prayer shawl at the Western Wall, the holiest place where Jews can pray, an act that police prohibit because of Orthodox Jewish sensitivities.
Anat Hoffman said police strip-searched her and jailed her overnight, releasing her only after she agreed to stay away from the site for a month. The incident occurred as she led prayers for 200 American Jewish women from Hadassah, a Jewish women's group that was celebrating its 100th anniversary.
Over the years, the growing religious influence, coupled with a high cost of living, has pushed tens of thousands of secular Jerusalemites to leave the city. Navigating a complicated balancing act, Mayor Nir Barkat, a secular, former high-tech businessman, has attempted to revive secular life in the city without alienating the ultra-Orthodox.
Barkat's office says the mayor has boosted the city's culture budgets since he was elected in 2008, quadrupling events like concerts and street festivals to enliven the city and encouraged new housing in secular areas to draw young couples and families.
"Despite a small number of friction points in the city, Jerusalem has seen a dramatic reduction in tension between the Ultra-Orthodox and secular communities in recent years," said spokesman Barak Cohen.
In a sign that secular life could be making a comeback, the mayor's office noted that enrolment in secular schools increased in the last school year for the first time in 15 years.
Naomi Tsur, a deputy mayor of Jerusalem, noted that for the first time in 15 years, there is a clear non-Orthodox majority in the city council, another sign of secular revival. Modern Orthodox schools also posted slight gains.
Whether these trends can continue remains unclear. More than 60 per cent of Jewish students attend ultra-Orthodox schools, according to the Jerusalem Institute of Israel Studies.
Tsur, an urban planner who has promoted coexistence among Jerusalem's diverse populations, said "a lot will hinge" on whether the secular masses turn their concerns into election issues. "People usually go to vote on 'shall we go to war with Iran,' but we need to work together on making an appealing mix that will attract young and dynamic couples to live in Jerusalem," she said.
With parliamentary elections set for January, Kiryat Yovel activist and art historian Daniel Unger thinks these issues will continue to be pushed to the back burner.
"This is a real issue that (Prime Minister Benjamin) Netanyahu and others don't want to address," he says. "Instead, he keeps talking about the Iranian bomb, in hope that his people won't pay attention to the domestic social and economic issues he's ignored."