Donald Trump says he’ll protect America by keeping bad people out. In a TV ad, he paints a grim picture of a Hillary Clinton presidency: “Syrian refugees flood in. Illegal immigrants convicted of committing crimes get to stay. … Our border open.” If Trump wins, the ad promises a better future: “America is secure. Terrorists and dangerous criminals kept out. The border secured. Our families safe.”

It’s natural to think of safety this way, especially when you’re a small child. You’re safe in your home with Mom and Dad. The bad guys are outside. Lock the door. But as you grow up, you learn that bad things can happen within. You can accidentally start a fire. Your parents can get cancer. Someone in your family can get hooked on alcohol or drugs.

The same thing happens in countries. Threats from abroad are usually obvious. Threats from within aren’t. Trump has never absorbed this lesson. He ignores the fact that native-born Americans are, if anything, more likely to commit crimes than immigrants are. He fixates on the possibility of ISIS operatives in the refugee population, failing to grapple with the more serious problem of ISIS-inspired attacks by native-born Americans. He demands “extreme vetting” of Muslims to protect the Constitution, obscuring the greater threat that he, as president, would pose to civil liberties. The peril to our way of life isn’t coming from Mexico or Syria. It’s coming from Trump.

Trump isn’t wrong to worry about ISIS operatives posing as refugees. That has happened in Europe. Two months ago, CIA Director John Brennan warned Congress that ISIS “is probably exploring a variety of means for infiltrating operatives into the West, including refugee flows.” But conservatives who quote that line ignore Brennan’s next two sentences. “As we have seen in Orlando, San Bernardino, and elsewhere, ISIL is attempting to inspire attacks by sympathizers,” Brennan pointed out. He noted that in May, “a senior ISIL figure publicly urged the group’s followers to conduct attacks in their home countries.”

This is the principal threat from ISIS: not that its operatives will sneak into the United States, but that through the internet, they’ll radicalize and trigger attacks by Americans who are already here. That’s one conclusion of an analysis published in December by George Washington University’s Program on Extremism. Brennan was referring to a May 21 message to ISIS sympathizers from the group’s spokesman, Abu Muhammad al-Adnani: “Truly, the smallest act you do in their lands is more beloved to us than the biggest act done here; it is more effective for us and more harmful to them. If one of you wishes and strives to reach the lands of the Islamic State, then each of us wishes to be in your place to make examples of the crusaders.”

Trump’s only answer to this problem is to complain that the parents of native-born American Muslims such as the Orlando, Florida, and San Bernardino, California, shooters shouldn’t have been allowed into this country. He offers no solution. He has no plan to deal with the channel through which ISIS arms its American sympathizers: easy access to guns. That was the warning delivered by a captured ISIS recruit to the New York Times earlier this month:

“[ISIS leaders] know it’s hard for them to get Americans into America [from Syria]. … For America and Canada, it’s much easier for them to get them over the social network, because they say the Americans are dumb—they have open gun policies. They say we can radicalize them easily, and if they have no prior record, they can buy guns, so we don’t need to have no contact man who has to provide guns for them.”

Even if Trump managed, through vetting, to prevent future terror attacks, he wouldn’t provide the security he’s promising to most Americans. Being shot by a roving ISIS nut is a suburbanite’s idea of danger. If you live on the South Side of Chicago, you’re a lot more worried about being shot by somebody who lives in your neighborhood.

When Trump pretends that American families would be safe if “illegal immigrants” were “kept out,” he’s defying the evidence. Native-born Americans are more likely to commit crimes than immigrants are. That’s because immigrants, particularly those who don’t have papers, are here to make a living and—more so than people who were born here—are afraid to get in trouble with the law. Statistically, when you look at the inverse relationship between immigration rates and crime rates, keeping immigrants out would seem to make you more likely, not less, to be victimized.

Nor would Trump’s tightening of borders protect national security. If you’re an enemy of the United States, killing three, 14, or even 49 Americans at a time isn’t enough. The real jackpot in the art of infiltration—the ultimate Trump card—is to subvert the whole country from the top. That’s what former Soviet spymaster Alexander Orlov told the CIA more than half a century ago: The most ambitious “line of Soviet intelligence” was “to influence the decisions of foreign governments through secret agents occupying important positions within them.”

Trump isn’t a Russian agent. He’s what communists once called a useful idiot: a naïve, easily manipulated spouter of ideas that serve foreign interests. He enjoys Vladimir Putin’s flattery and serves Putin’s interests by weakening NATO and defending Russia’s seizure of Crimea. Trump also serves the interests of ISIS and al-Qaida by framing the struggle against them as a battle between the West and Islam. On Wednesday, at a rally in Jackson, Mississippi, Trump and Nigel Farage, the chief promoter of Britain’s vote to leave the European Union, congratulated one another for breaking the shackles of Western alliances. Putin must have laughed.

But the greatest threat Trump poses to the United States isn’t his aid to foreign enemies. It’s what Hillary Clinton outlined in a speech on Thursday: his direct assault on American values. He has explicitly challenged birthright citizenship, the independent judiciary, freedom of the press, and the legitimacy of American elections. He has advocated torture, plunder, political violence, voting against candidates based on ethnicity, and a religious test for entrance to the country. Trump says he’ll vet Muslim immigrants to make sure they respect our values. But no immigrant could pose a fraction of the danger that Trump, from the White House, would present to the soul, the Constitution, and the survival of the United States.

Many Republicans want to believe that in the past week or so, Trump has mended his ways. He hasn’t. He continues to defend racial profiling and threaten American-born Muslims. In a town hall aired on Fox News on Wednesday night, he repeated his pledge to abolish the 14th Amendment’s guarantee of citizenship to children born in the United States.

Trump’s new message is the same as his old message: He’ll lock the doors, protecting you from everyone but him. At a rally in Tampa, Florida, on Wednesday, he promised “a new ideological screening program to keep out people who don’t share our values.” We’re “allowing them in by the tens of thousands,” Trump jeered. “How stupid are we?”

Good question. On Nov. 8, we’ll find out.

Read more Slate coverage of the 2016 campaign.