Winston Churchill once famously said that Americans could always be counted upon to do the right thing after exhausting all other possibilities. In the bloody aftermath of the Brussels attacks, Mr. Churchill appears to have been an optimist.

Republican presidential candidate Ted Cruz responded to Tuesday’s terrorist strikes by offering the campaign’s most destructive policy proposal since Donald Trump pledged to ban all Muslims from entering the United States. In an embarrassing race to the bottom, the Texas senator hatched an Orwellian plot to lay siege to American neighborhoods populated by worshipers of Islam. This harebrained scheme is every bit as harmful to the West’s fight against the Islamic State as Trump’s Muslim ban. Not only does the Cruz proposal send the worst signal to Muslims worldwide, but also it wipes away a natural advantage the United States has enjoyed over every other country since the Mayflower first set sail for the new world.

Today, Europe finds itself locked in a perpetual war against Islamic terrorists because Belgium, France and other European Union countries cannot integrate Muslim immigrants into their cultures. Add a disastrous open borders policy to the mix, and a refugee crisis that has rendered European leaders incapable of balancing rational security concerns with noble humanitarian instincts, and you have the makings of a crisis that David Ignatius calls the greatest threat ever faced by modern Europe.

If Americans want to inherit those problems, all they need to do is follow the Texas senator’s lead. But doing so would also be ignoring 240 years of American history.

The United States has long absorbed immigrants from Ireland, Italy, Germany, the Soviet bloc, Vietnam and countless other countries. That process has not always been pretty, but our melting pot has done the trick more often than not. And in a country that was overwhelmingly white and Protestant for its first 200 years, those immigrants often worshiped differently than the rest of us. But out of many, one.

Immigrants like Intel’s Andy Grove and Google’s Sergey Brin led companies that fueled the United States’ explosive growth and created a new age for the rest of the world. In fact, half of all new Silicon Valley companies started between 1995 and 2005 were created by immigrants drawn by the promise of the America Dream. Like a professor named Einstein who helped the United States win World War II, many of these men and women left their adopted country better than they found it. And somewhere in our country today is a young American who, like Steve Jobs, had parents from Syria — or Jordan or Iraq — who came to the United States in search of a better life and greater freedom, not more religious tests or targeted surveillance schemes.

American Muslims deserve better than what Ted Cruz is offering. And come to think of it, so do we all.