"People here are the real Turkey," she said, waving a flag high above her head.

It is an emotional reaction to a relatively new layering of society that began 20 years ago but has accelerated recently. A massive migration from rural areas to Turkey's cities and a large-scale economic boom have drawn an entirely new class of religious Turks from the country's heartland into the life of its secular cities.

The class is represented by Prime Minister Recep Tayyip Erdogan, who is challenging the secular elite, forcing a presidential candidate upon them whom they find completely distasteful.

On Friday, the military gave him a warning. It has ousted four elected governments since 1960, and seemed to be considering whether to make Erdogan's the fifth. On Sunday, Erdogan gave a warning of his own: He will continue to push his candidate, an action that will probably lead to early national elections.

Secular Turks fear that Erdogan has a secret agenda to impose Islamic law on Turkey and that his party's move to secure the presidency, the highest seat of secularism in Turkey, is one of the final steps needed to start that process.

Erdogan, for his part, came from Turkey's political Islamic movements of the 1990s, but he broke with them and formed his own, which swept national elections in 2002. He has said that he would keep religion out of policy decisions, and for the most part, he has.

But for the protesters on Sunday, that was not enough.

"They say they've changed, but look at their wives," said Yalcin Turkdogan, 61, an architect who had not been to a protest since 1977. Erdogan's wife wears a head scarf.

For Sevim Erzen, a retired civil servant at a protest in Ankara earlier this month, the number of women in head scarves moving into her wealthy Istanbul neighborhood was disturbing. " They have started to look down on us," she said. "They are trying to be part of the ruling class."

The message of secularist protesters, said Metin Heper, a professor at Bilkent University in Ankara, was this: "We are uncomfortable with the lifestyles of these people."

"They fear these people, but these fears are groundless," he said. "Gradually, they will see that these people are no different from themselves."

Prejudices among secular Turks have their roots in Turkey's education system, Heper said. "Education here teaches that if you are a practicing Muslim, you are an ignorant person who will bring the country back to the Middle Ages," he said.

M. Hakan Yavuz, the author of "Islamic Political Identity in Turkey," describes being shocked at the rigidity in the political science department at Ankara University, where he got his undergraduate degree, compared with the village where he grew up, where interpretations of the teachings of a thinker of Sufism, a mystic branch of Sunni Islam, were welcomed everywhere.

"It was not a dialogue, but rather a carefully structured program of indoctrination," Yavuz writes in the preface of his book, published by Oxford University Press in 2003, referring to his education at Ankara.

One of the problems for the secularists is that the elite never fully redefined the legacy of Mustafa Kemal Ataturk, the visionary who founded the Turkish state in 1923. It did not change with the times. The main secular political party, the Republican People's Party, lacks agile leaders who can articulate a unifying vision for the diverse secular groups.

They never had to. The most recent attempt by a pro-Islamic party to run the country, in 1997, ended in the military pushing it out of power.

Gokay Gedik, a 20-year-old student at Marmara University here who had come to the protest on Sunday with his friends, all members of the same rock band, said the Republican People's Party was all talk and no action.

"Blah, blah, blah," added his friend, who had a pierced eyebrow and dreadlocks.

Secular Turks worry that the new class of religious migrants could potentially be a force for radicalism. Large groups of new migrants to cities propelled revolutions in Iran and in Russia.

But in Turkey, the class owns businesses and has become better off in the recent economic boom. It values stability in society.

The new mingling in secular urban areas has had a quieter effect, raising emotional questions like whether to separate the sexes in public swimming pools or change the curriculum in schools to include more religious instruction.

Questions about how tolerant the new class of society will be of secular lifestyles is of vital importance to secular Turks, but they go unaddressed by Erdogan's party. In part, that is because the party is under fire by the secular establishment, which seizes on any opportunity to find evidence of Erdogan's Islamic influence.

"Even if Erdogan walked on water, the secularists wouldn't believe him," said Morton Abramowitz, a former American ambassador to Turkey who is a senior fellow at The Century Foundation, a nonpartisan research group.

Erdogan dodges direct discussion of religion, preferring instead to cite his party's glowing economic achievements, which his secular critics often dismiss. "Some have eyes but cannot see," he said in a speech this month. "Some have tongues but cannot speak the truth. They have ears but can't hear. That's where the problem is."

Then, in an earnest cry of incomprehension: "What makes you souncomfortable?"

But his silence has fed the worries of secular Turks, who fear that their freedoms will be curtailed by the rank and file of Erdogan's party, who have grown up in conservative communities largely separated by sex.

"There is a feeling of my rights being taken away," said Guldal Okutucu, the leader of the women's branch of the Republican People's Party, "of pressure that tries to push me into a secondary role."