It happened on Parshat Vayera. The worst anti-Semitic attack in American history occurred while Jews around the world were reading the Torah portion that tells the story of Lot, an immigrant.

Lot moves to Sodom, and prospers there. The Midrash says he becomes a judge. His daughters intermarry with the locals. Then one day, while sitting at the gates of the city, the assimilating immigrant sees two strangers approach. He asks them to “spend the night and bathe your feet”— the Midrash says he learned to welcome strangers from his uncle Abraham, the first Jew. Lot “prepares them a feast.”

But in Sodom, the natives hate strangers. “Where are the men who came to you tonight?” they demand. “Bring them out to us.” Lot tries to protect his guests. “I beg you friends,” he implores, “do not commit such a wrong.” For the men of Sodom, however, this just underscores Lot’s foreignness. He hasn’t really assimilated; he isn’t one of them. He’s a threat. “The fellow came here an immigrant and already acts the ruler,” they declare. “Now we will deal worse with you than with them.”

Why did Robert Bowers murder eleven people yesterday at the Tree of Life Synagogue in Pittsburgh? We’re unlikely to ever fully grasp his motives. But he was enraged, it appears, by the fact that synagogues were participating in a program run by the Hebrew Immigrant Aid Society that dedicated special Shabbat services to the plight of refugees. “HIAS likes to bring invaders in that kill our people. I can’t sit by and watch my people get slaughtered. Screw your optics, I’m going in,” Bowers wrote hours before his attack. In another post, he declared, “Open you Eyes! It’s the filthy EVIL jews Bringing the Filthy EVIL Muslims into the Country!!”

Obviously, America is not Sodom. But Bowers tried to harm Jews, at least in part, for the same reason the men of that ancient city tried to harm Lot: Because Jews were welcoming strangers. Instead of assimilating into a culture suffused with anti-immigrant hatred, HIAS — which was founded to help Jewish immigrants to the United States —now assists immigrants and refugees from across the world.

For several years now, as anti-Semitism has risen in the United States and around the world, American Jews have argued with each other about how best to keep safe.

One camp says the best strategy is to ally with the Trumpian right. Sure, Trump and his supporters scapegoat Latinos and Muslims; they want to shut America’s doors to refugees. But according to polls, they like Jews. Jews, after all, have assimilated. Most speak unaccented English. Most are prosperous. Most are considered white.

Trumpians are thus generally willing to embrace Jews as real Americans so long as they reject any affinity with the newer immigrants who threaten America’s “Western” and “Judeo-Christian” identity. And many prominent Jews are happy to accept that bargain, and display their loyalty to Trump’s America by echoism his bigotry.

Sheldon Adelson — who thinks all terrorists are Muslim — is Trump’s biggest financial backer. Mort Klein, head of the Zionist Organization of America — who recently referred to “filthy Arabs” — is thrilled that Trump is trying to keep Muslims out of the United States. Last year, Republican Josh Mandel, who was running for the Senate in Ohio, retweeted a tweet declaring that, “I am so sick and tired of PC idiots worrying about offending Islam. I stand with Israel and my Judeo-Christian culture and I find Islam offensive.” Joel Pollak is senior-editor-at-large of Breitbart, which warns endlessly about the threat Americans face from depraved Muslim and Latino refugees.

There’s a moral argument against this strategy. As Parsha Vayera suggests, welcoming the stranger is among the most fundamental Jewish imperatives. Lot “baked unleavened” bread for the strangers who came to Sodom. The parallel to the exodus from Egypt is clear. Lot and Abraham welcomed strangers; Pharaoh oppressed them. And 36 times in the Torah Jews are reminded to be like Abraham and Lot: To remember the heart of the stranger because were strangers in the land of Egypt.

But putting the moral argument aside, even from the narrowest of self-interest, the Adelson-Klein-Mandel-Pollak calculation is foolish.

Bowers did not ask the Jews he murdered whether they support admitting refugees. He saw that some Jews support admitting refugees and he blamed us all. That’s how anti-Semitism works. No matter how much Trump’s Jews try to prove their loyalty to his racially and religiously exclusive vision of America, others Jews will not — and that will make all Jews vulnerable.

Bigots don’t make fine distinctions. If they don’t distinguish Muslims from ISIS and Latinos from MS-13, they won’t distinguish the congregants at Tree of Life Synagogue from George Soros.

Appeasement will not work. For Jews, the lesson of yesterday’s massacre is very simple and very old: Protecting the strangers among us is not charity. It is self-defense. Every time Jews defend the right of American Muslims to follow sharia, we protect our right to follow halacha. Every time Jews reject politicians who demonize Latinos we make it less likely that those politicians will demonize us. “Hate them, not us” is a losing strategy because once empowered, bigots widen their targets. For people who define America as a white Christian nation, Jews will never be white enough.

Robert Bowers accused Jews of “bringing” Muslims and refugees to the United States. To him and all the other white nationalists Trump has emboldened, our answer should be: Damn right. We will demand a humane policy for people seeking refuge in the United States and defend those immigrants — no matter their race or faith — who are already here.

Will do so not only because we were once strangers but because we know that, at some level, like Lot, we always will be. Rather than seeking a separate peace with Trumpism, we will look for allies among the despised and abused. And in that way, we will defend not only Jewish ethics, but Jewish lives.

Peter Beinart is a senior columnist at The Forward.