FBI crime scene investigators document the area around two deceased gunmen and their vehicle outside the Curtis Culwell Center in Garland, Texas, on Monday, May 4, 2015.

Hate and terrorism make a powerful, toxic stew. Especially when spiked by religion.

It was to the misfortune of Garland, Texas, that the witch's brew occurred over the weekend in that town of almost 227,000.

A man previously identified by the FBI as a jihadist terror suspect was one of the two gunmen killed Sunday after opening fire at an event where people were invited to present cartoons of the Prophet Muhammad, a law enforcement official said.

That's the terrorism part. Now for the hate:

The event was billed as a "free-speech event" organized by the American Freedom Defense Initiative, a New York-based group that also uses the name Stop Islamization of America. The event included a contest for the best caricature of the Prophet Muhammad, with a $10,000 top prize.

Drawings of the prophet are considered offensive in most interpretations of Islam. You will remember that in January, gunmen in Paris attacked the offices of Charlie Hebdo, a French satirical newspaper known for printing caricatures of the prophet and other religious leaders including the Pope, Jesus, Buddha -- you name it. A dozen people were killed in that terror attack. The 2005 publication of cartoons of Muhammad in a Danish newspaper prompted demonstrations and drew death threats, and four men were convicted of plotting a retaliatory attack on the newspaper.

But this event in Garland wasn't even pretending to be an ordinary newspaper's or magazine's satire that offers nonpartisan, or in this case nondenominational, lampooning. This event was plainly inviting haters and their hated to clash.

The president of American Freedom Defense Initiative (sounds innocent, doesn't it?) and Stop Islamization of America (sounds like the intolerant hate group that it is) is Pamela Geller.

The Southern Poverty Law Center lists the American Freedom Defense Initiative as an active anti-Muslim group in its "Extremist Files" database. The center terms Geller "the anti-Muslim movement's most visible and flamboyant figurehead."

"All anti-Muslim hate groups exhibit extreme hostility toward Muslims," according to the SPLC, which tracks hate groups.

Geller told CNN that the "Muhammad Art Exhibit and Cartoon Contest" in Garland was a response to January's Charlie Hebdo attack in Paris, and the group specifically picked Garland's Curtis Culwell Center, a school district-owned facility, because it hosted an event denouncing Islamophobia in January.

But you might also recall that Geller and friends have been at work here in Tennessee.

In June of 2013, Geller was among of group of outside political activists who turned a Manchester, Tenn., public forum meant to help people understand the differences among free speech, hate speech and threats into something more akin to a KKK rally.

The meeting, in a region that saw an 83 percent increase in Muslim and foreign-born residents between 2000 and 2008, was launched by a Facebook post by Coffee County Commissioner Barry West. He had posted an illustration of a man with one eye closed as he squinted down the sights of a double-barreled shotgun pointing at the camera. The image was captioned "How to wink at a Muslim."

Geller and friends -- many in cars bearing license plates from Texas, Florida, South Georgia and Virginia -- shouted down the speakers, including U.S. Attorney Bill Killian and representatives of the American Muslim Advisory Council.

Three years before, Geller also spoke to Tennessee tea party groups in Gatlinburg. She called President Barack Obama "the culmination of the Islamic-leftist alliance" and decried the planned construction of a 13-story mosque near the site of the 2001 terrorist attacks in New York. And, yes, it was also her group that demonstrated in New York.

Have you wondered why many followers of Islam object to drawings of the prophet Muhammad?

The reasoning follows a central tenet of Islam: the worship of God alone. The prohibition began as an attempt to ward off idol worship, according to CNN.

"The prophet himself was aware that if people saw his face portrayed by people, they would soon start worshiping him," according to Akbar Ahmed, who chairs the Islamic Studies department at American University, told CNN. "So he himself spoke against such images, saying 'I'm just a man.'"

Mohamed Magid, an imam and former head of Islamic Society of North America, told CNN that the Muslim prohibition on depicting prophets extends to Jesus and Moses, whom Islam also treats as prophets. Some Muslim countries banned the films "Noah" and "Exodus" this year because their leading characters were Hebrew prophets.

But that's not the message of Geller and her faux freedom talk. Instead, her so-called "free-speech event" was designed to poke a teabilly bully finger into the eyes of someone different with different beliefs.

Not only is that kind of intolerance dangerous, it's disrespectful of who we are in America. We are a nation of immigrants -- here because our ancestors sought America's freedom of religion and freedom of speech. Yet hate groups like Geller's -- and like the extremists who attacked -- seek confrontation rather than understanding. They blur those freedoms, and they court the violent senseless attacks like we saw Sunday.