It is different, and less disturbing, to target the nationality of potential entrants, rather than their religion. It is the difference between Trump proposing, say, a temporary moratorium on visas for people coming here from Pakistan and Saudi Arabia — San Bernardino terrorist Tashfeen Malik was a Pakistani who spent a lot of time in Saudi Arabia — and a halt to all Muslims. Trump’s ban would apply to an Iraqi interpreter who worked alongside U.S. troops, as well as to a harmless Ph.D. from Malaysia.
Still, the braying about the First Amendment from the Left is rich. The implicit position of Trump’s progressive critics is that the First Amendment doesn’t protect all political speech, or cover people with religious objections to gay marriage, or prevent the Obama administration from forcing nuns to sign up for contraception coverage, but it extends to foreigners hoping to gain entry into the United States.
The embedded assumption is that migrating here is some sort of global civil right. Republicans, too, are subject to this hazy thinking. Trump may be ignorant and bombastic, but his supporters believe that, if nothing else, he understands that the security and interests of Americans must come first. They know no such thing about his hysterical detractors.