The attacks in Paris have inspired a xenophobic bidding war among Republican presidential candidates.

Gov. Bobby Jindal on Monday signed an order trying to get his state of Louisiana to block the settlement of any Syrian refugee, while Mike Huckabee, the former Arkansas governor, proposed we “wake up and smell the falafel” and said House Speaker Paul Ryan should resign if he can’t block the refugees’ arrival. Candidates Ben Carson, Marco Rubio, Rand Paul and John Kasich also joined the jingoistic bid to block Syrian refugees.

In a particularly pernicious twist, Jeb Bush and Ted Cruz both floated the notion Sunday of admitting Christian refugees from Syria but not Muslims.

The religious test for refugees originated, as nasty things often do, in the mouth of Donald Trump, who proclaimed in July — falsely — that Christians fleeing Syria “cannot come into this country” but Muslim refugees from Syria “can come in so easily.” Trump, later alleging — again falsely — that President Obama wanted to admit 250,000 Syrians, said he would deport refugees, who he speculates are “mostly men” and perhaps part of an Islamic State terrorist plot. (On Monday he said he would “strongly consider” closing mosques.)

This isn’t just talk: In September, Rep. Mike McCaul (Tex.), chairman of the House Homeland Security Committee, led a group of Republicans in introducing legislation that would legalize discrimination against Muslims fleeing Syria by giving priority to Christians and other religious minorities. As The Post’s Abby Phillip documented, more than a dozen governors joined Jindal on Monday in trying to keep Syrian refugees from their states.

This growing cry to turn away people fleeing for their lives brings to mind the SS St. Louis, the ship of Jewish refugees turned away from Florida in 1939. It’s perhaps the ugliest moment in a primary fight that has been sullied by bigotry from the start. It’s no exaggeration to call this un-American.

Or un-Christian. Among those distressed by the latest turn in the GOP primary is the National Association of Evangelicals. “We’re saddened and shocked about what happened in Paris,” said Matthew Soerens, spokesman for World Relief, the evangelical association’s humanitarian arm. “But we don’t think the response should be to close our doors to closely vetted people coming from Syria.”

Soerens argued that:

●Rather than Trump’s male-heavy flood of 250,000 coming to the United States, only 2,200 Syrians have been admitted in the past four years (10,000 are expected over the next year) and 70 percent have been either women or children under age 14.

●The situation here is “entirely different” from Europe, where Syrian refugees are flooding across borders. Here, an ocean away from the conflict, they aren’t admitted until they are vetted for at least 18 months.

●No terrorist incident has ever been traced to somebody admitted through the American refugee resettlement program.

●A plurality of refugees admitted to the United States from all destinations are Christian. A disproportionate number of refugees from Iraq admitted to the United States have been Christian. And while most — but not all — of the Syrian refugees so far are Muslim, this makes sense because “it’s a mostly Muslim country and most of the victims are Muslim.”

In the days since more than 120 people were killed in a terrorist attack in Paris, conservative presidential candidates have called for limiting the number of Syrian refugees allowed into the U.S. (Sarah Parnass/The Washington Post)

So why pursue a claim that is as false as it is cruel? Perhaps the GOP hopefuls are having trouble differentiating themselves from Obama on the broader issue of Syria. For all the criticism of his approach to the Islamic State, several supposed alternatives are things that have already been tried: airstrikes, arming the opposition, special forces, social-media propaganda. Other ideas would require combat ground troops in Syria, which no candidate but long-shot Sen. Lindsey Graham (S.C.) has championed.

There’s a solid case to be made against Obama’s handling of the Islamic State that doesn’t require Republicans to go nativist. His strategy clearly hasn’t worked so far, and he continues to struggle to articulate his strategy. At his news conference in Turkey on Monday after the G-20 conference, Obama’s first five questioners ranged from skeptical to hostile:

“Is it time for your strategy to change?”

“Have you underestimated their abilities?”

“Do you think you really understand this enemy?”

A defensive Obama said his critics “seem to think that if I was just more bellicose in expressing what we’re doing, that that would make a difference.”

Nobody asked about the Republicans’ refugee rhetoric — so Obama, in need of a change of subject, brought it up himself. He called it “shameful” and called on leaders “not to feed that dark impulse inside of us.”

Obama’s response to the question nobody asked was downright bellicose, with an admirable moral clarity missing from his Islamic State strategy. A worthy opposition would demand more force and clarity from Obama on the Islamic State — not make scapegoats of a small number of innocents fleeing for their lives.

Twitter: @Milbank

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