Earlier this year, hundreds of people turned out in Yorba Linda, California to protest the appearance of two highly controversial Muslim speakers at a dinner held to benefit local charitable projects. The scene outside the social hall quickly turned ugly, even frightening.

At first, some protesters just criticized the speakers. Then a local politician, Villa Park Councilwoman Deborah Pauly, characterized the fundraiser as “pure, unadulterated evil.” She declared that she knew “quite a few Marines who will be very happy to help these terrorists to an early meeting in paradise.”

Later, a breakaway group of some 100 enraged protesters screamed at the Muslims arriving for the dinner, many with small children in tow.. They chanted “Go back home!” and hurled extremist insults: “Muhammad was a child molester! You beat your wife and you rape your children! Take your sharia and go home, you terrorist lovers!”

This demonizing outburst was just one manifestation of an apparent wave of anti-Muslim paranoia now sweeping the nation.

Over the past two years, an astonishing number of Americans have become convinced that Muslims, a tiny percentage of the U.S. population, are on the verge of trampling the Constitution and imposing Islamic culture and law.

The latest surge in anti-Muslim xenophobia dates to the 2008 elections, when President Barack Obama’s political opponents portrayed him as a covert Muslim. They falsely claimed he was some kind of foreign-born Manchurian candidate or terrorist sympathizer–even though he was born in Hawaii and clearly worships as a Christian. The Pew Research Center found in an August 2010 poll that nearly one five in Americans believed Obama was a Muslim, a big increase from surveys taken in 2009.

Unsurprisingly, the increase in the number of Americans questioning Obama’s religious preference coincided with the controversy over a planned Islamic cultural center near the site of the 9/11 attacks in Manhattan. That outcry, and the people who ginned it up, likely did more to stoke anti-Muslim sentiment than anything else in recent years.

A Gallup poll last month found that more than one in four Americans believe that Muslims who live in the United States support al-Qaeda.

Lawmakers in state legislatures from Oklahoma to Alabama have introduced Islamophobic bills to ban the use of Islamic religious law, called sharia, in our courts. This is remarkable since this could never happen under our Constitution. In our schools, educators report rising harassment of Muslim students and teachers, along with efforts by activists to dictate that Islam be presented to students as un-American and dangerous.

News reports strongly suggest a spike in anti-Muslim hate crimes. Last May, for example, a bomb exploded at an Islamic Center in Jacksonville, Florida. In August, a man slashed the neck and face of a New York tax driver after finding out he was a Muslim. Four days later, someone set fire to construction equipment at the future site of an Islamic center in Murfreesboro, Tennessee. Hate crime statistics for 2010 won’t be released by the FBI until later this year, but it appears certain they will show increasing attacks against Muslims.

The first such spike in anti-Muslim hate crimes occurred in the immediate aftermath of 9/11, when they soared by more than 1,600 percent over the previous year, according to FBI statistics. The initial rage has now morphed into a more generalized fear of Islam itself. It’s an evolution from specific concerns to general stereotyping that’s a typical pattern of racism and xenophobia.

A small coterie of highly vocal activists, using angry rhetoric and xenophobic propaganda, are stoking this rage. They’re aided by irresponsible media figures and politicians who amplify their message of intolerance to further stigmatize Muslims.

Following the surge in anti-Muslim hate crimes after 9/11, President George W. Bush delivered a series of speeches in which he assured Americans that Muslims weren’t our enemy. His message resonated, and hate crimes quickly and dramatically declined.

Conservative politicians should follow Bush’s example and condemn the hate speech that’s again endangering Muslim Americans, instead of continuing to fuel the fire.