A U.S. Customs and Border Protection Office (CBP) agent and...

A U.S. Customs and Border Protection Office (CBP) agent and Border Patrol agents participate in an operative to find illegal migrants at the International Bridge Paso del Norte-Santa Fe in Ciudad Juarez, Chihuahua State, Mexico on July 1, 2019. Credit: AFP/Getty Images/HERIKA MARTINEZ

In August 2016, a secret Facebook group for current and former Border Patrol agents was created called “I’m 10-15,” agency code for “aliens in custody.” It has 9,500 members and, according to an expose by the journalistic website ProPublica published this week, features hateful and dehumanizing discussion of immigrants. Its existence should enrage all Americans, and the way the group entices members to embrace their worst selves should make us think about how hatred flourishes or is defeated.

The size of the closed group itself is both hilarious and daunting. You can probably have a secret Facebook page with five people and keep it under wraps, or even 50. But 9,500 people? That’s not a social media klatch, it’s a town.

What’s most disturbing about the membership of 9,500, though, is that the Border Patrol has only 20,000 agents. “I’m 10-15” is no splinter group of rare and rotten apples. It represents a significant portion of the Border Patrol community.

So what’s the gang gabbing about? Members got some laughs from a 16-year-old Guatemalan male who died in May while in Border Patrol custody in Texas. One response included a picture of an Elmo puppet saying, “Oh well.” Another said, “If he dies, he dies.”

A post of the now-famous Associated Press picture of a father and his 23-month-old daughter, both dead and sprawled facedown in the Rio Grande, said the photo might be fake because “we’ve all seen the dems and liberal parties do some pretty sick things.”

And “I’m 10-15” posters were particularly upset about a visit this week by members of the Congressional Hispanic Caucus to Southern border detention facilities, singling out Reps. Veronica Escobar and Alexandria Ocasio-Cortez for scorn. One member asked agents to “hurl a burrito at these bitches.” Another, a patrol supervisor, wrote “[expletive] the hoes.” And doctored pictures showed Ocasio-Cortez forced to perform oral sex on President Donald Trump.

I’ve avoided the debate about whether the detention facilities can be called concentration camps because it’s a waste of energy better used to argue that we should do more to meet the challenge of treating these people humanely, processing them, and sending them home or releasing them.

But the way members of “I’m 10-15” talk about immigrants in the country illegally is the way the Nazis who ran the concentration camps and the German citizens who did nothing to stop the Holocaust spoke about and thought of Jews and Gypsies and homosexuals. They dehumanized these people so completely that their abuse and killing seemed trifling.

One can oppose illegal immigration without dehumanizing and despising the people coming here for a chance at the extraordinary life the United States offers. That’s fair.

But when we attack and diminish these immigrants for where they came from, or encourage violence against them or their allies, or tolerate our president or our Border Patrol or even our pals doing so, we place ourselves on the same slippery slope that the Nazis and slave owners and those who blithely massacred American Indians skidded down. And there is nothing an influx of immigrants could do to this nation that would be worse than allowing ourselves to slide down that familiar slope again.

 Lane Filler is a member of Newsday’s editorial board.