The 61-year-old clergyman is now in the midst of a polarizing political, religious and cultural debate over plans for a multistory Islamic center that will feature a mosque, health club and theater about two blocks north of ground zero. He is one of the leaders of the Park51 project, but has largely been absent from the national debate over the implications of building a Muslim house of worship so close to where terrorists killed more than 2,700 people.
Though Rauf has said the center, which could cost more than $100 million, would serve as a space for interfaith dialogue, moderate Muslim practice and peaceful prayer, critics say it will create a base for radical, anti-American Islam. Some critics have also asked where the funding for the center might originate and whether it may come from sources linked to Muslim extremists.
Former House Speaker Newt Gingrich, a potential 2012 presidential candidate, called the backers of the project "radical Islamists." "They're trying to make a case about supremacy" with the center, he said.
The American Jewish Committee has said that while Park51's leaders have a right to build their center, they must "fully reveal" their sources of funding and "unconditionally condemn" terrorism inspired by Islamist ideology before they can obtain the organization's support.
Those who know Rauf and have worked with him say that he is anything but extreme in his beliefs or intentions.
"He is one of the really important Muslim leaders in America, working for and working with other religions," said the Rev. James Parks Morton, the former dean of the Episcopal Cathedral of St. John the Divine who has known Rauf and his family for more than 30 years. "He's a very, very conciliatory, intellectual guy."
During the past few months, Rauf has been in Malaysia, where his family has long-standing ties, and on a State Department-financed goodwill tour of Gulf countries.
Through a spokesman and his wife, he declined to speak with The Associated Press in recent weeks. His few interviews lately have been with local Arabic media during his State Department tour.
He told the daily Bahrain newspaper Akhbar Al-Khaleej on Aug. 24 that he blamed the news media, in part, for strained relations between Muslims and Americans. Rauf said the media "has succeeded in portraying stereotypical images, focusing on the negative and criticizing the other."
With Rauf largely absent from the debate, opponents have scoured past statements and critics portray the imam as tone-deaf to the sensitivities of families who lost relatives on Sept. 11. They argue he should forthrightly condemn Arab political movements such as Hamas that the U.S. government has designated as terrorist organizations.
Asked in June by WABC-AM whether he believed the State Department was correct in designating Hamas as a terrorist organization, Rauf gave a winding response: "I am not a politician. ... The issue of terrorism is a very complex question. ... I do not want to be placed ... in a position of ... where I am the target of one side or another."
Rauf rarely deviates in his interviews, speeches and books from a core message of the need for interfaith dialogue to resolve religious conflicts. What emerges is a portrait of a man who has passionately argued that Islam is inherently compatible with American life, and that each is enriched by the other.
He has strongly opposed acts of violence in the name of Islam.
"The Quran allows fighting only in defense - when we are attacked or thrown from our homes or denied our basic rights because of what we choose to believe," he writes in his 2004 book.
"But even in those cases where fighting is allowed, the Quran never allows the killing of innocent people."
The annex of his book includes a 2001 fatwa, or religious ruling, signed by five Islamic scholars, that permits Muslims to fight for U.S. forces in Afghanistan.
He also writes that there is no circumstance under which the Prophet permitted suicide, and says so-called "martyrdom operations" are unsupported by Islam.
"It is a phenomena that no civilized society - in the Muslim world or the West - should be content to accept," he said.
Rauf was born in Kuwait, the son of an Egyptian imam and noted Islamic scholar, Muhammad Abdul Rauf, who came to New York City in the 1960s and helped lead efforts to establish the Islamic Cultural Center of New York, the city's first building designed as a mosque. The multimillion-dollar project took more than 25 years and opened in 1991. The elder Rauf also led the Islamic Center of Washington before taking a job in Malaysia.
The younger Rauf didn't follow his father's path into religion until later in life. He studied physics at Columbia University and in New Jersey, and dabbled in teaching, sales and real estate. He married, first to an American who converted to Islam, and a second time to a Malaysian woman. He has two children from each of the marriages.
In the late 1990s, he married his third wife, Daisy Khan, who has actively supported the Islamic center proposal.
In 1983, Rauf was asked to lead prayers at a small mosque in lower Manhattan, 12 blocks from the World Trade Center site and near the Park51 project. The mosque, Masjid al-Farah, was created by a Sufi order called Nur Ashki Jerrahi, currently led by a woman, which means the order of light and love. Sufism is a mystical tradition that emphasizes a direct and personal experience of God through chanting and other acts of devotion, and is known for adapting to local culture.
Rauf is especially popular among young, urban professionals.
Author Asra Nomani said she once attended a retreat organized by Rauf and Khan, and noted that Rauf allowed parallel prayer sections for men and women - a rare practice. In the majority of mosques, women sit behind men, shielded by a room divider.
"Imam Feisal, he has always been on a moderate course - many of us would call it a liberal-progressive course," said Saleemah Abdul, 36, who works for the United Nations and is editor of a book on American Muslim women. "He has promoted women's leadership, youth leadership in a time and a place where many Muslims felt isolated and alienated."
Rauf helped to establish the American Society for Muslim Advancement and the Cordoba Initiative, two organizations with missions to build dialogue between Muslims and the West.
His travels have been financed partly by the U.S. government, which has been sending him on diplomatic trips to Muslim nations since the Bush administration. Contributions to his nonprofit organizations have come from American groups like the Rockefeller Brothers Fund and the Ford Foundation, government agencies in Qatar and the Netherlands, and the Kingdom Foundation, a philanthropy affiliated with Saudi prince Alwaleed bin Talal, the largest shareholder in Citigroup.
After the Sept. 11 attacks, Rauf was called on repeatedly by news organizations to help explain to Americans why the U.S. was so hated by some factions in the Muslim world.
Some of his comments then have now been seized on by critics as evidence of anti-American views.
"We tend to forget, in the West, that the United States has more Muslim blood on its hands than al Qaida has on its hands of innocent non-Muslims," he said in a 2005 lecture in Australia. "You may remember that the U.S.-led sanction against Iraq led to the death of over half a million Iraqi children. This has been documented by the United Nations."
Rauf told an interviewer in July that about a decade ago he envisioned a global association of Muslim community centers modeled after the Young Men's Christian Association, serving as centers of interfaith dialogue and spreading moderate Islam worldwide.
The first of these Cordoba Houses, as he initially referred to them, would be established in New York City.
"Our stated objective is to establish this as a launching point, as a headquarters if you want, of a global understanding, of a moderate Islam that is true to its fundamental principles," he told the New York-based Intersections International, a group that has endorsed the Islamic center. "And to accuse us as being the opposite of that flies in the face off our stated vision, our mission, my track record and everything I've ever done or stood for."