What happened when Saudi Arabia closed its borders to Christian immigrants

(The Conversation is an independent and nonprofit source of news, analysis and commentary from academic experts.)

Pardis Mahdavi, Pomona College

(THE CONVERSATION) Donald Trump has made exclusion a troubling touchpoint of his campaign, through his inflammatory proposal to block Muslim refugees or with the removal of a Muslim woman from one of his rallies.

Other Republican presidential hopefuls have also expressed anti-immigrant, anti-Muslim sentiments. Ted Cruz repeatedly refused to criticize Trump’s Muslim ban. Ben Carson called for a registry of all Muslim immigrants to the U.S.

Democrats have gotten into the act, too. The new Visa Waiver Reform Bill (HR 158), recently passed in the House with bipartisan support, would make movements into the U.S. by Muslims more difficult. The bill requires that individuals – even European Union citizens – acquire a visa before re-entry to the U.S. after visiting Muslim majority countries such as Syria or Iran.

Before U.S. politicians and European leaders like Alexis Tsipras of Greece or Hungarian Prime Minister Viktor Orban push ahead with...