The Southern Poverty Law Center claimed that Act for America is "the largest grassroots anti-Muslim group in the country”, and the Council on American-Islamic Relations has described it as "one of the main sources of growing anti-Muslim bigotry in our nation". According to The Guardian, the organization has been "widely identified as anti-Muslim".

When Gabriel was invited to speak as part of a lecture series organized by Duke University's Jewish community in October 2004, many in attendance were angered by her referring to Arabs as "barbarians." The Freeman Centre for Jewish Life at Duke University later apologized for her comments.

In 2007 at the Christians United for Israel annual conference, Gabriel delivered a hate speech that included the following:

“The difference, my friends, between Israel and the Arab world is the difference between civilization and barbarism. It's the difference between good and evil... this is what we're witnessing in the Arabic world. They have no soul, they are dead set on killing and destruction. And in the name of something they call "Allah" which is very different from the God we believe...”

In response to her critics, Brigitte Gabriel has said that "I am not anti-Muslim, I am anti ideologies which want to kill free people and subjugate them right now, in the name of the Islamic religion. I would fight with the same passion if crazy Christians were trying to do that, if crazy Jews were trying to do that, or whatever crazy religious is trying to do that. I am for the human spirit and for the individuality of the human spirit." She argued that there are innocent Muslims who have not even read the Quran, and that she is deeply acquainted with some Muslims. 

Ms. Gabriel, who uses a pseudonym, casts her organization as a nonpartisan, nonreligious national security group. Yet the organization draws on three rather religious and partisan streams in American politics: evangelical Christian conservatives, hard-line defenders of Israel (both Jews and Christians), and Tea Party Republicans. She presents a portrait of Islam so thoroughly bent on destruction and domination that it is unrecognizable to those who study or practice the religion. She has found a receptive audience among Americans who are legitimately worried about the spread of terrorism.

“America has been infiltrated on all levels by radicals who wish to harm America,” she said. “They have infiltrated us at the CIA, at the FBI, at the Pentagon, at the State Department. They are being radicalized in radical mosques in our cities and communities within the United States.”Through her books, media appearances and speeches, and through her organization, ACT! for America, Gabriel has become one of the most visible personalities on a circuit of self-appointed terrorism detectors who warn that Muslims pose an enormous danger within the borders of the United States.

In May of this year Belen Fernandez wrote “The simplicity of her message is also easily digested by Western masses in search of a convenient domestic and global scapegoat” in her attempt to define Gabriel’s message. She goes on to say that “All of this might be somewhat laughable if Gabriel and her organization didn't boast a substantial public following, made all the more worrying by her access to corridors of power.” Last December, Gabriel wrote that “ACT for America has a direct line to Donald Trump, and has played a fundamental role in shaping his views and suggested policies with respect to radical Islam.” In March 2018, a Vox article detailed the "deep and extensive ties" maintained by United States President Donald Trump's latest high-level appointees, John Bolton and Mike Pompeo, to "an organized group of anti-Muslim writers and activists" including Gabriel.

Since Trump has become president, the unthinkable has become not only thinkable, but pedestrian. The president and his aides have transgressed prior standards of decency and honesty in so many ways that it’s sometimes hard to remember what those standards even were; yet alone uphold them. BuzzFeed News described her as "the most influential leader in America’s increasingly influential anti-Islam lobby." Peter Beinart of The Atlantic describes her as "America's most prominent anti-Muslim activist."