NEW YORK – Pamela Geller’s apartment, in the fashion of the blogosphere, doubles as her office. It is a modern full-floor unit in a high-rise on the East Side of Manhattan that could belong to a socialite or the editor of a lifestyle magazine. There is ample light and a tasteful lack of clutter. The kitchen appliances are made of brushed steel; the countertops are slate. In the earth-toned living room hangs a painting, in vibrant colors, of a woman in a swimsuit.

It is in this genteel setting that Geller, 52 and a single mother of four, wakes each morning shortly after 7, switches on her laptop and wages a form of holy war through Atlas Shrugs, a website that attacks Islam with a rhetoric venomous enough that PayPal at one point branded it a hate site. Working here – often in fuzzy slippers – she has called for the removal of the Dome of the Rock from atop the Temple Mount in Jerusalem; posted doctored pictures of Elena Kagan, the Supreme Court justice, in a Nazi helmet; suggested the State Department was run by "Islamic supremacists"; and referred to health care reform as an act of national rape.

Geller has been writing since 2005, but this summer she skyrocketed to national prominence as the firebrand-in-chief opposing Park51, the planned Muslim community center she denounces as "the ground zero mega-mosque."

Operating largely outside traditional Washington power centers, Geller, with a coterie of allies, has helped set the tone and shape the narrative for a divisive national debate over Park51 (she calls the developer a "thug" and a "lowlife"). In the process, she has helped bring into the mainstream a concept that after 9/11 percolated mainly on the fringes of American politics: that terrorism by Muslims springs not from perversions of Islam but from the religion itself. Her writings, rallies and television appearances have both offended and inspired, transforming Geller from an Internet obscurity into a media commodity who has been profiled on "60 Minutes" and whose phraseology has been adopted by Newt Gingrich and Sarah Palin.

For Geller, the battle against Park51 is only part of a much larger crusade in which she is joined by an influential if decentralized coalition that includes former generals, new-media polemicists, researchers and evangelicals who view Islam as a politically driven religion, barbaric at its core and expansionist by nature. Her closest partner is Robert Spencer, the proprietor of Jihadwatch.org. Incorporation papers for their American Freedom Defense Initiative list as founding members Anders Gravers, a Danish "anti-Islamization" activist ("Jihad is the knife slicing the salami of freedom"), and John Joseph Jay ("There are no innocents in Islam"). Their lawyer, David Yerushalmi, has sought to criminalize the practice of Islam.

Atlas Shrugs, which gets about 1 million unique visitors a month, helped draw thousands to protests against Park51 on June 6 and Sept. 11. Geller, supported by a divorce settlement and blog advertisements, also played an important role in winning the resignation in 2007 of Debbie Almontaser, a Muslim principal who started an Arabic-language public school in Brooklyn; brought 200 people to Ohio last year to support Rifqa Bary, a Muslim girl who accused her parents of abuse; and helped draw vociferous objectors to a hearing this summer on a since-scrapped proposal for a mosque on Staten Island.

"I think she’s enabling a real bigotry – a lot of people are convinced by the propaganda she repeats like a mantra," said Charles Johnson, who runs the blog Little Green Footballs, where Geller got her start as a frequent commenter.

The day last December when The New York Times first reported plans to build a Muslim community center two blocks from ground zero, Atlas Shrugs immediately objected. "I don’t know which is more grotesque," Geller wrote, "jihad or the NY Times preening of it."

She dropped the topic until May 5, when the project – including a mosque, sports facilities and cultural programs to promote understanding between Muslims and non-Muslims – won unanimous approval from a committee of Community Board 1.

The next day, Atlas bristled with outrage.

"This is Islamic domination and expansionism," Geller declared. The only Muslim center appropriate near ground zero, she said, would be devoted to "expunging the Quran" of "incitement to violence."

Two days later, Geller invited readers to protest the "9/11 monster mosque being built on hallowed ground zero," in a post that was among the first to spread the misimpressions that the project was at the World Trade Center site and would solely house a prayer space. The next week, The New York Post took up the cause ("Mosque Madness at Ground Zero"). Fox News booked Geller on Mike Huckabee’s television program. Sean Hannity hosted her on the radio.

Next, the organization she and Spencer took over in April, Stop Islamization of America, held a rally on the anniversary of D-Day, which Geller marks as the moment Park51 became a national sensation. A post about it by El Marco, a conservative blogger, "went viral," she said, a rare instance of a big debate’s bursting on the scene without "the mainstream media telling people what to think."

Geller, though, had some suggestions. She and other bloggers quoted selectively from the imam, Feisal Abdul Rauf, stressing his description of U.S. policy as partly responsible for 9/11. They branded him a "radical Islamist." They declared that his talks against extremism and violence were "taqiyya" – the hiding of true beliefs, religiously sanctioned for Muslims, usually minority Shiites, under hostile rule. And Geller said, without evidence, that the center’s financing might be tied to terrorists.

Her assertions became common talking points for Republican leaders and other opponents. Soon, Rick A. Lazio, running for governor of New York, was calling the imam a "terrorist sympathizer." Rush Limbaugh was describing Park51 as a "victory mosque."

Pamela Geller was born in 1958, the third of four girls. She grew up in Hewlett Harbor, one of Long Island’s Five Towns, an affluent, heavily Jewish enclave.

The sisters went to Hebrew school, but attended synagogue mainly on Rosh Hashana and Yom Kippur. Israel, which now forms a crucial piece of Geller’s politics, was not frequently discussed.

Geller said her early years were imbued with a sense of American power and rectitude, so pervasive that it need not be articulated. Many of her current concerns – political correctness, media cowardice, changing national identity, eroding individual rights – can be connected to those times.

"Growing up as the sort of tail end of the baby boomers, there was this feeling of invincibility in America," she said. "We were free. The good guys won. The good cop is on the beat. I certainly don’t get a sense of that anymore."

It was 9/11 that drove Geller to her keyboard. She had barely heard of Osama bin Laden, she said, and "felt guilty that I didn’t know who had attacked my country."

She spent the next year educating herself about Islam, reading Bat Ye’or, a French writer who focuses on tensions over Muslim immigrants in Europe; Ibn Warraq, the pseudonym for a Pakistani who writes about his rejection of Islam; and Daniel Pipes, whom she ultimately rejected because he believes in the existence of a moderate Islam.

Geller commented prolifically on websites focused on Islamic militancy, like Little Green Footballs.

A fellow commenter called Pookleblinky urged Geller to start her own blog. She named it in homage to Ayn Rand’s championing of individual rights and, perhaps, to conjure the weight of the world on her shoulders.

Readership grew steadily. A next turning point for Geller was a "counter-jihad" conference in Brussels. It threw her – and Spencer of Jihad Watch – together with anti-Islamic Europeans whom even some allies considered too extreme.

Geller went on to champion as patriotic the English Defense League, which opposes the building of mosques in Britain and whose members have been photographed wearing swastikas. (In the interview, Geller said the swastika-wearers must have been "infiltrators" trying to discredit the group.) And she formed a lasting partnership with Spencer.

It is partly philosophical: They and the anti-Islam movement in Europe share a fear of Muslim takeover. And it is partly practical: He helps her raise money and source some assertions; she helps him spread his ideas and, he said, "get results."

Then Park51 emerged.

It is difficult to determine who finances their movement, since their new organization has yet to win tax-free status requiring documentation of donations. Spencer estimated that since 2009, the two have raised and spent about $150,000 for things like the bus ads and giant television screens for the 9/11 rally, some of it donated through Spencer’s Jihad Watch, a 501(c)3 nonprofit agency. In recent years, Jihad Watch has been a program of the David Horowitz Freedom Center, which pays him a $132,000 salary and, as Politico.com has reported, has received significant contributions from philanthropists who back the Israeli right.

Asked how much her blog collects in reader donations and advertisements (one promotes a creationist website), Geller said only that it was enough to live on.

She is barreling ahead. Just last week, Atlas called on readers to boycott Campbell’s soup after the company announced that it planned to certify some products as halal – the Muslim equivalent of kosher – with the supervision of a group that Geller considers a front for terrorists.

"Warhol," she wrote, "is spinning in his grave."