Republican presidential front-runner Donald Trump’s recent declaration that he would ban Muslims from entering the country served as a tipping point for many leaders, uniting a range of politically and theologically diverse clerics who are denouncing anti-Muslim sentiments.

Citing the nation’s history of religious freedom and tolerance, a group that included Catholic, Jewish, Muslim and evangelical leaders placed an ad in Monday’s Washington Post saying “Muslims are our equals.”

The leaders called remarks from political leaders “highly offensive,” and said suggestions that a Muslim cannot be president or that Muslims should be registered and their mosques closed are unconstitutional. “As faith and community leaders that value our own freedom of religion, we state unequivocally that we love our Muslim siblings in humanity,” they wrote.

The first to sign was Cardinal Theodore McCarrick, who said that many Americans are scared and are starting to say things they don’t really mean.

“I’m scared of the crazy fringe. I’m troubled by it,” he said. “It’s not the world I want to live in.”

McCarrick, who was archbishop of Washington from 2001 to 2006, said, when the country chooses to follow the fringe, then it has lost its balance.

“I’m 85 years old, I’m no chicken,” McCarrick said. “Freedom of speech is very important, but hatred is also very important and very dangerous.”

Those who signed the letter echoed a similar call from other religious leaders last week at Georgetown University, including Cardinal Donald Wuerl, the archbishop of Washington, who condemned intolerance. Vice President Joe Biden joined religious leaders Dec. 16 to denounce the anti-Muslim rhetoric. Regionally, Muslims have seen support from religious leaders in communities like Miami, Philadelphia and Columbus, Ohio.

Monday’s letter was signed by 49 religious and civic leaders.

“We are all aghast at the debate,” said Chris Seiple, a longtime advocate on international religious freedom who has advised the State Department. “Normally, there’s nothing that brings us together, except that we believe in inherent human dignity rooted in freedom of conscience and belief.”

Seiple said that leaders were especially troubled by the last GOP debate, when Republican candidates only referred to American Muslims as those who can “help us defeat the enemy.”

“It wasn’t that they are citizens, that they are Americans, that they have common values,” Seiple said. “They are seen as a utilitarian point of access to defeat the enemy.”

The letter was co-sponsored by the Inclusive America Project of Aspen Institute’s Justice & Society Program and the Shoulder-to-Shoulder Campaign, partially underwritten by businessman and former U.S. ambassador to Denmark, John Loeb Jr., and the George Washington Institute for Religious Freedom.

The Shoulder-to-Shoulder Campaign, which is funded by a large grant from the Open Society Foundation, was launched in 2010 during a controversy over a mosque near the World Trade Center memorial in New York. Campaign Director Catherine Orsborn said that leaders are seeing an intensity of anti-Muslim sentiment at a whole new level this year.

“We’re seeing this rhetoric hitting public stages pretty regularly, and it’s empowering people on the fringes,” Orsborn said. In September, Republican presidential candidate Ben Carson said the United States should not elect a Muslim president and Trump suggested he would consider shutting some mosques down. But anti-Muslim sentiment has especially intensified since the attacks in Paris and the shootings in San Bernardino, California.

Rabbi Jonah Pesner, head of advocacy and social justice for the largest segment of Judaism, the Reform Movement, said he has encouraged Jews to light an extra candle during Hannukah to show solidarity with Muslims.

Pesner said that his own grandmother came to the United States in 1916 to escape pogroms aimed at Jews in Russia.

“I’m not going to stand idly by as my Muslim neighbor bleeds, or a Sikh or a Hindu or a Catholic or any other religious person who came here to be free,” Pesner said. “It was Jews yesterday, Muslims today, who will it be tomorrow?”

Constitutional issues about religious freedom were debated and resolved more than 200 years ago, said Suhail Khan, a Muslim who worked in the George W. Bush administration and was one of the people who organized the letter.

“Oftentimes the most hateful voices are the most loud and most strident and get the most attention,” Khan said. “We may not be the loudest, but we have history behind us.”