President Trump signs an executive order on Friday temporarily barring people from seven predominantly Muslim countries from entering the United States. (Susan Walsh/Associated Press)

THE EXECUTIVE ORDER that President Trump signed on Friday calling a temporary halt to travel to the United States from seven predominantly Muslim nations — and indefinitely blocking refugees from the world’s largest humanitarian crisis, in Syria—is an affront to values upon which the nation was founded and that have made it a beacon of hope around the world. George Washington declared in 1783 that the “bosom of America is open” not only to the “opulent and respectable stranger” but also “the oppressed and persecuted.” Now Mr. Trump has slammed the door on the oppressed and persecuted in a fit of irrational xenophobia.

He ordered foreign nationals from Syria, Iran, Sudan, Libya, Somalia, Yemen and Iraq be barred immediately from entry into the United States for 90 days while more rigorous visa screening is put into place. This touched off panic and chaos at airports on Saturday as people with already-issued visas were turned away from boarding flights and others detained on arrival. Among those caught in the mess and held at John F. Kennedy Airport in New York was an Iraqi who had worked for the United States in Iraq for a decade. Green card holders, already permanent residents in the United States who happened to be overseas, were told they could no longer re-enter. Untold thousands of people who have applied for visas — including translators and interpreters who have worked with U.S. forces in Iraq — were left wondering if they would ever make it to American shores.

Syria’s civil war has forced about 4.8 million people to flee to neighboring countries, and 1 million are seeking asylum in Europe. Mr. Trump callously and without evidence declared that Syrian refugees are “detrimental to the interests of the United States,” although in fact the relatively small number who have come to the United States have proven overwhelmingly positive. Mr. Trump’s four-month ban on refugees from these predominantly Muslim nations was accompanied by an instruction to prioritize refugee claims made by religious minorities facing persecution, chiefly Christians whose communities have suffered greatly over many decades. We think there’s a legitimate place in refugee policy for favoring persecuted minorities, but favoring one faith while blocking people from another is demeaning to all and runs counter to the basic tenet that the United States does not discriminate by religion.

Mr. Trump claims these seven countries might produce terrorists who “will use any means possible to enter the United States.” The country that supplied 15 of the 19 hijackers in the 9/11 attacks is Saudi Arabia, which is not on Mr. Trump’s list. Vigilance is always called for, but refugees to the United States are as a whole grateful and hard-working and have not resorted to terrorism. Cutting them off not only punishes the most vulnerable, but may encourage terrorist recruitment and violence.

Mr. Trump’s actions pander to rage and fear of outsiders. Yet our long history shows these fears are unfounded. The diversity, experience and striving of immigrants and refugees have immeasurably strengthened the United States; outbursts of anti-alien sentiment have only weakened it.