I remember vividly my first visit to Ground Zero. It was August 2002 and flags, wreaths, cards and floral bouquets still adorned the streets around the 16-acre hole in the ground. One particular image lingers: a navy blue T-shirt, emblazoned with the logo of the New York City Fire Department, on which a mourner had written: "We will never forget the brave firefighters who were killed by terrorists on September 11". Someone had crossed out the word "terrorists" and replaced it with "Muslims". As a Muslim, I could only despair at the repugnant notion that all Muslims, and indeed Islam itself, shared responsibility for 9/11. But time, I reassured myself, would be a great healer.

I was wrong. Fast forward to the present: August 2010. A $100m proposal to build a facility for Muslims in lower Manhattan, called Cordoba House, has become the focus of an intense controversy. Outraged rightwing protesters have spent several months trying to block the construction of what they call the Ground Zero mosque, claiming it is an "insult" to the victims and a "victory" for the terrorists.

Ignorance and bigotry abounds. Cordoba House is not a mosque but a cultural centre, which will include a prayer area, sports facilities, theatre and restaurant. The aim of the project is to promote "integration, tolerance of difference and community cohesion … a place where individuals, regardless of their backgrounds, will find a centre of learning, art and culture". Nor is it being built at Ground Zero. The proposed site is two blocks to the north.

Neither of these inconvenient facts, however, have stopped a slew of high-profile Republicans falling over one another to denounce the project. The former Alaska governor Sarah Palin, in her now-notorious tweet, urged "peaceful Muslims" to "refudiate" the proposed "mosque", because it "stabs hearts". Former New York mayor Rudy Giuliani said the project was a "desecration" and the former Speaker of the House of Representatives, Newt Gingrich, declared that "there should be no mosque near Ground Zero so long as there are no churches or synagogues in Saudi Arabia".

The craven silence of leading Democrats is equally unforgivable. President Obama, accused by some opponents of being a "secret Muslim", has yet to utter a single word in support of the project.

Meanwhile, across the US, intolerance of Islam and Muslims is growing. In recent weeks, there have been public protests against new mosques in Temecula, California, and in Murfreesboro, Tennessee. A church in Gainesville, Florida, has plans for a "Burn a Qur'an day".

Unlike many Muslims, I have always been an Americanophile. I know the majority of Americans are decent people, committed to freedom and tolerance. Don't believe me? The mayor of Gainesville has condemned the idea of a "Qur'an-burning" day. In Temecula, the number of locals who turned out to support a new local mosque outnumbered protestors by four to one. In New York, a poll revealed that more Manhattanites were in favour of the "Ground Zero mosque" than were against it, including businessman Charles Wolf, who lost his wife in the attack on the twin towers.

And on Tuesday, New York mayor Michael Bloomberg made an impassioned speech to his fellow Republicans in which he argued that Muslims "are as much a part of our city and our country as the people of any faith", adding: "To cave to popular sentiment would be to hand a victory to the terrorists".

The mosque row has become a struggle for the soul of the United States, the nation where freedom and democracy is supposed to reign supreme. As both a Muslim, and a friend of America, I hope and pray that the decency of Bloomberg and Wolf triumphs over the bigotry of Palin and Gingrich.