This piece originally appeared on the Huffington Post.

A disloyal religion. A religion that mandates violence. A religion incompatible with freedom. A religion intent on overthrowing the government. A religion that’s not a religion but a political movement.

Such smears were used for years in American politics to attack Roman Catholics, and Catholic immigrants in particular. In the 19th century, rioters attacked Catholic churches and homes, and an entire political party was created based on the fear of a Catholic plot to undermine America. The Ku Klux Klan reorganized in the early 20th century in part by using anti-Catholicism to recruit members. 

While John F. Kennedy’s 1960 Houston speech on the separation of church and state and his subsequent election were seen as turning points, religious bigotry never went away in American politics; the targets simply shifted, as the very same attacks once hurled against Catholics are now being used to demonize and marginalize Muslims. 

This year, Donald Trump showed once again that religious bigotry remains an effective and destructive way for politicians to foment hate and win political power.

Muslims were among Trump’s top targets of scorn and ridicule in his successful presidential bid. He falsely claimed that Muslims took to the streets by the thousands to celebrate 9/11; declared that “Islam hates us”; repeated a debunked story about Muslims refusing to report the terrorists behind the San Bernardino attack; proposed banning all Muslims from entering the U.S.; considered a Muslim registry and database; baselessly alleged that around one out of three Muslims were ready to go to war against the U.S.; and praised a general who he said massacred his Muslim detainees with bullets washed in pigs’ blood. 

Trump’s attacks against America’s Muslim community capitalized on existing anti-Muslim bigotry that has been diligently spread by a network of far-right groups. But he brought those bigoted ideas to a far wider audience, feeding anti-Muslim conspiracy theories directly into the national media. Unsurprisingly, his election has led to a spike in attacks against Muslim-Americans.

On the campaign trail, Trump surrounded himself with anti-Muslim conspiracy theorists like Michael Flynn, who is now set to be his national security adviser, and Steve Bannon, whom he has named his top White House strategist.

Flynn, a board member of the anti-Islam group ACT for America, has described Islam as “a cancer” and “a political ideology” that “hides behind this notion of it being a religion.” If Islam isn’t a religion, activists like Flynn believe, then Muslims shouldn’t receive First Amendment protections.

On his Twitter page in August, Flynn posted a video that said “ISIS is practicing Islam to the letter.” He has tweeted that Muslim leaders must “declare their Islamic ideology sick.” “Fear of Muslims is RATIONAL,” he said in one tweet promoting a video that said Islam “wants 80% of humanity Enslaved or EXTERMINATED.” 

Before joining Trump’s team, Bannon ran the ultraconservative website Breitbart, which he boasted was the “platform for the Alt-Right,” a racist and xenophobic movement. Under Bannon’s leadership, Breitbart was dominated by stories about the purported dangers of Muslims, and promoted the Alt-Right narrative that the West is engaged in a civilizational war with the Islamic world.

This rhetoric, incidentally, plays into the very message that terrorist groups like ISIS are attempting to promote: that their version of Islam is the only true one and that they are engaged in a civilizational battle against the West. Mara Revkin and Ahmad Mhidi noted in Foreign Affairs over the summer that Trump’s rhetoric had the potential to be a valuable recruiting tool for these groups. Both ISIS and Al Qaeda celebrated Trump’s win by claiming that it validated their claim that the U.S. hates Muslims.

Even before his inauguration, Trump’s religious bigotry is wreaking real damage on America, undermining national security and giving the green light to a wave of assaults against Muslim-Americans.

Perhaps Trump can learn from Abraham Lincoln, a man he claims to admire, who called out as hypocrites politicians who claimed to believe in liberty while seeking to exclude Catholics and immigrants from fully taking part in American society.

Judging by his pick of advisers, however, it seems unlikely that President Trump will be that much different than the man we saw on the campaign trail, a man willing to sow divisions and ratchet up bigotry no matter the cost.