JERUSALEM — Speaking to a group of ultra-Orthodox men shortly before he officially entered politics, Yair Lapid, a proudly secular talk-show host, declared that in a century-long competition to define Israel’s character, “we lost and you won.”

“Not only in terms of numbers,” Mr. Lapid said in late 2011 at a college for religious students, but also in politics “and as a consumer force and in the streets and in the culture and in the educational system — you won in all these places.”

Now, Mr. Lapid’s stunning success in last week’s election, in which his new Yesh Atid became Israel’s second largest party, is being viewed by many voters, activists and analysts here as a victory for the secular mainstream in the intensifying identity battle gripping the country.

The catchphrase of Mr. Lapid’s populist campaign, and now a core principle of the negotiations to create Israel’s next governing coalition, is “sharing the burden.” That refers directly to lifting the widespread draft exemptions for the ultra-Orthodox, integrating them into the work force, and shifting the balance of who pays taxes and who receives government aid. But it is also code for a broader sociological shift, a call to push back against the ultra-Orthodox minority’s outsize influence in the public sphere, including efforts to gender-segregate buses, sidewalks and stores in their neighborhoods and strict rabbinical controls on marriage, divorce, conversion and adoption statewide.

“All of a sudden there was a change in seculars in Israel — they see themselves also as a sector that needs to fight for themselves,” said Mickey Gitzin, director of Be Free Israel, a group founded in 2009 that advocates for equality and religious pluralism. “People say, ‘Wait a minute, I don’t see myself as part of a society where women cannot sit in the front of the bus.’ People don’t want to be part of such an extreme society.”

Shmuel Jakobovits, an ultra-Orthodox rabbi who runs the Torah Institute of Contemporary Issues in Jerusalem, said he, too, sees the election as about far more than how many yeshiva students should be drafted.

“The community is growing, and it’s perceived as a potential threat to the character of the rest of the country,” Rabbi Jakobovits said. “The underlying issue is that there’s an ideological contest over the soul of the state of Israel and the Jewish people.”

In a survey of Israeli Jews last summer conducted for another pro-pluralism group, Hiddush, 47 percent identified the religious-secular divide as the most acute in society, more than twice as high as the next ranked choice of politics, at 19 percent, followed by rich and poor, at 15 percent. In a separate Hiddush poll the week before the election, 67 percent said a party’s position on matters of religion and state — including the draft and civil marriage — would influence their vote.

“There are elements in the making of a Kulturkampf,” said Uri Regev, a Reform rabbi who runs Hiddush, using the 19th-century German term for culture war. “These issues have a way of coming out and messing up solidarity, messing up politics. It’s time to deal with them in a way that is a root canal; that’s what’s necessary.”

The ultra-Orthodox, known here as Haredim, now make up nearly 10 percent of the Jewish population, up from 6 percent a decade ago. But their concentration in some Jerusalem neighborhoods and certain cities around the country — often helped by huge, subsidized housing projects geared to their large families — has led many less-religious Jews to flee from what they call Haredization.

Clashes have increased along with the population shift. Buses have stopped running advertisements depicting people because portraits of women were constantly vandalized. Religious soldiers have boycotted military ceremonies where women sing. Those who drive on the Sabbath are sometimes harassed. And in late 2011, an international uproar was set off when a group of Haredi men spit at an 8-year-old Modern Orthodox girl on her way to school, calling her a prostitute because her clothing was seen as not modest enough.

“I am so tired of the ultra-Orthodox,” Merav Basher, 39, said to explain her vote for Yesh Atid, Hebrew for There is a Future. “I wanted to make sure to give them as little power as possible.”

Ms. Basher lives in Modiin, a city halfway between Jerusalem and Tel Aviv where there was a recent flare-up with a neighboring Haredi community over access to public parks. Mr. Lapid received 27 percent of the vote there. He did even better in well-to-do Tel Aviv suburbs like Hod Hasharon, Kfar Shmaryahu and Savion, leading many to describe Yesh Atid as a “white tribe” of upper-class descendants of Eastern European Jews.

“If there’s one thing Israelis hate, it’s to be a frier,” said David Tal, 50, a tour guide from Modiin, using a slang Hebrew term for “sucker.” “The Haredim have become an issue which makes people feel like suckers, and Lapid connected to that.”

Mr. Lapid, 49, is hardly the first politician to galvanize the secular middle class into a voting bloc. His father, Yosef Lapid, known as Tommy, did so a decade ago with the Shinnui Party. But the elder Mr. Lapid “was much more militant and much more aggressive,” said Benjamin Brown, a professor of Jewish thought at Hebrew University, citing cartoons he thought bordered on anti-Semitic and slogans suggesting Haredim were “the source of all evil in our society.”

The younger Mr. Lapid, in contrast, recruited two Orthodox rabbis to his slate for Parliament, and he talks about uniting Israel’s tribes. “Definitely the music is different,” said Professor Brown, who is also a researcher at the Israel Democracy Institute. “Maybe it really reflects a difference in essence. I’m not sure.”

The first test will be the issue of the draft. The Supreme Court last spring invalidated a law exempting thousands of yeshiva students from serving, but the government has so far failed to come up with a plan for integrating them.

Mr. Lapid, who won 19 of Parliament’s 120 seats and has emerged as a power broker in the negotiations to form a new government, wants to cut the exemptions to a few hundred and impose sanctions on those who do not serve. He also wants to require more math, science and English in Haredi schools.

But there is staunch opposition from the ultra-Orthodox, who have been part of nearly every coalition since 1977, gaining leverage as their numbers have grown, to 16 lawmakers in the current government from 10 in 1992. Last week, two Haredi parties, Shas and United Torah Judaism, won 18 seats combined, which their leaders have pointed out is one shy of Mr. Lapid’s showing.

“If they try to compel the Haredim,” Meir Porush of United Torah Judaism told the Israeli newspaper Maariv, “then we are heading toward a deep rift.”

Beyond the draft, Mr. Lapid’s party platform said it would “work to promote” civil marriage, including for same-sex couples, and “rectify inequality in family laws.” On his Facebook page, Mr. Lapid wrote that “as far as women’s exclusion is concerned there can be no compromise or negotiation.”

In the speech to the ultra-Orthodox at Ono Academic College, Mr. Lapid spoke pointedly about overhauling the draft and the core curriculum, but also called for a sort of détente.

“I realize you don’t want your kids to play with my kids in the public playground, and I try very hard not to take offense,” he said. “But there’s no reason why we can’t find a way to live next door to each other without my having to fear that you’ll proselytize my kids, and without you having to fear that I’ll corrupt your kids.”