Republican presidential candidate Donald Trump speaks during the Values Voter Summit on Sept. 25, 2015, in Washington. (Jose Luis Magana/AP)

During a panel called “The Islamic Threat,” retired Army Lt. Gen. William Boykin stood behind a conference-room podium at the Values Voter Summit last weekend and told his listeners that, while there are good Muslims in the United States, Islam is unlike any other religion and should not be protected by the First Amendment.

“No religion that threatens our Constitution can be protected under that Constitution,” Boykin, now executive vice president of the Family Research Council, said firmly. He added that “16 percent of Islam is religion. The rest of it is political.”

Boykin was joined by Cathy Hinners, founder of a Tennessee-based Web site devoted to “exploring and exposing Islam in America.” She reminded listeners that “in the time of Muhammad, mosques were centers” for military activity.

And panelist Sandy Rios, head of governmental affairs for the American Family Association, told the crowd that a “peaceful” Islam is a “delusion.”

Rather than dissipate after 9/11 and the eventual killing of Osama bin Laden, the deeper range of fears about Muslim dangers to the United States have only proliferated in blogs, books, videos and speeches among true believers. Now those fears are bursting to the forefront of the GOP presidential contest, and polls show they have become commonplace among Republican voters.

Last month, GOP front-runner Donald Trump did not challenge a questioner who said at a town hall meeting, “We’ve got a problem in this country — it’s called Muslims,” and who asserted that President Obama is a secret member of the faith. The man also asked Trump about getting rid of Islamic “training camps” on American soil, to which Trump replied: “We’ll be looking at that.”

Days later, Ben Carson, who is polling second, said a Muslim should not be president, arguing that tenets of the faith are not “consistent with the constitution.”

And Texas Sen. Ted Cruz told Fox News that Obama “has acted as an apologist for radical Islamic terrorists.”

Polls suggest these statements play well with GOP primary voters. In a 2013 New York Times-CBS poll, 60 percent of Republicans surveyed said they viewed Islam in a negative light. Last year, the Cooperative Congressional Election Study found that 54 percent of Republicans believe President Obama is “deep down” a Muslim.

And this week, a USA Today/Suffolk University poll found that while 63 percent of Democrats said they would be willing to vote for a Muslim, only 26 percent of Republicans said they would be willing to do so.

The Republican party platform also expresses concern about “radical Islam,” using the term twice in the context of national security. Republican National Committee spokesman Michael Short did not respond to calls or e-mails for comment.

At the Values Voter Summit, the language was far more extreme. Now in its 10th year, the event — sponsored by groups including the legislative arms of the Family Research Council and the American Family Association — has become a must for Republican candidates hoping to win evangelical support.

This year, several major presidential aspirants appeared at the two-day event, which featured forums mixing general concerns of conservative Christians (“Reclaiming America God’s Way — Using Biblical Principles”) with anger at Planned Parenthood, outrage about gay marriage and worry about the threat posed by Islam.

One speaker was Brigitte Gabriel, president of Act! for America. The Southern Poverty Law Center describes Gabriel as “head of the largest grassroots anti-Muslim group in the country.”

Gabriel’s books — “Because They Hate” and “They Must Be Stopped,” both alarmist tracts about Islam — have sold a combined 120,000 copies in print, not counting e-books, according to Nielsen BookScan, which usually tracks about 70 percent of print sales. She has 40,000 followers on Twitter and her Facebook account has 207,000 likes.

In an address to the full gathering of summit participants, Gabriel described Islam as a “political movement cloaked in religion,” adding that 77 percent of the world’s “moderate Muslims” agree with the establishment of the Islamic State.

Turning to 2016, she urged listeners to elect a president who makes the world realize this is a “person you’re not going to mess with. Because he could care less about what you think, what the U.N. thinks, what the world thinks. They can all go to hell. We care about America and only the United States of America!”

To applause and cheers, she added, “This election is about survival — our survival and the survival of western civilization.”

Experts say Gabriel far overstates the level of domestic threat. Fears of secret radical Muslim infiltration into the United States have abounded since 9/11 and are almost always at a “high simmer,” said Ryan Lenz, who investigates anti-Muslim bias for the SPLC.

Still, Lenz said, “When anybody can find one of these terrorist training camps they keep talking about, I’ll stand corrected.”

Diana West, author of “American Betrayal: The Secret Assault on Our Nation’s Character,” draws corollaries between today’s issue with Muslims and the Communist red scare of the 1940s and 1950s (she says Joseph McCarthy’s House Un-American Activities Committee was heroic and on point, rather than paranoid and vindictive, as nearly all historians say) .

“It’s more of a grass-roots issue, probably still more on the outsider side of things,” West said. “But now with Dr. Carson . . . speaking out, it’s drawn more attention because he’s a prominent voice on the right. It’s drawing mainstream attention.”

Trump, too, has amplified anti-Islamic fears by making wild, unsubstantiated charges that only seem to push him higher in the polls, said Sydney Van Morgan, director of the International Studies Program at Johns Hopkins University in Baltimore.

Considering all this from Arizona is Zuhdi Jasser, a retired U.S. Navy commander and founder of the American Islamic Forum for Democracy, which promotes a moderate, if not progressive, version of Islam. Jasser often warns about the dangers of “Islamists” to conservative audiences, but he draws a sharp line between those and the rest of the flock.

“I often feel like a ping-pong ball between the left, which wants to think Islam is all about peace, and the other party, who thinks my faith is the problem,” he said.

At the Values Voter Summit, the overwhelming message was that the West is under a sustained, cloaked assault from Islam — culturally, ideologically and militarily — and that most Americans are either naive, ignorant or deluded about its dangers.

Hinners has written, for example, that the Common Core is actually a secretly Muslim-backed plot to indoctrinate American school children. During the panel on Islam, Boykin said some American Muslims are conducting “jihad of the womb” — having as many babies as possible to build their base on U.S. soil.

In the audience was David Marco, a field officer for a California medical products company. Afterward, Marco said he was “certain that the vast majority of Muslims are fine people.” But 9/11 was a shock to the nation, he said, and while most of America has “bent over backwards to be nice,” he’s been disappointed that so many Muslims seem to have “stuck to their original positions.”

Frank J. Gaffney Jr., a former Reagan appointee in the Defense Department, now runs the conservative Center for Security Policyand publishes monographs with titles such as “Star Spangled Sharia.” He said more people are beginning to recognize the “civilizational Jihad” that targets “the church, academia, the media, financial institutions, the government, and on and on.”

This, he says, coupled with international events such as the failure of reform in Egypt, the rise of the Islamic State and the subsequent tide of refugees in Europe, is persuading Americans that the threat is upon them.

“Largely neglected until fairly recently has been the kind of focus we thought warranted on the more subversive elements, such as pre-violent jihad,” he said in an interview. “I think it’s beginning to be accepted . . . by the public before elected officials or partisans of either political stripe.”

The panel on Islam, in fact, was subtitled “Women Who Know the Truth — The Latest to Make SPLC’s Hate List,” a jab at an SPLC report earlier this year that listed a dozen women among the most virulent anti-Muslims in America (this included all the women on the panel).

“There are instances of radical Islam in the U.S., and there are instances of Muslims being radicalized and carrying out attacks on U.S. soil,” Lenz said. “But they use these events as bullhorns to decry an entire faith as being violent.”

At the end of the panel discussion, Rios of the American Family Association hit a final point: The Muslim Brotherhood and their politically correct allies have been able to silence critics by accusing them of prejudice, she said. The Obama administration has been shamefully silent. And the mainstream media has been cowed, except for Fox News (where she is a frequent contributor) — “and even they have to be careful.”

With an absence of political leadership and dangers abounding, “it’s up to us to educate ourselves, isn’t it?” she said.

The panelists got a standing ovation.