Furthermore, there is even precedent for it:
Is an immigration ban on Muslims unconstitutional? Probably not. The Supreme Court has held consistently, for more than a century, that constitutional protections that normally benefit Americans and people on American territory do not apply when Congress decides who to admit and who to exclude as immigrants or other entrants. This is called the plenary power doctrine. The Court has repeatedly turned away challenges to immigration statutes and executive actions on grounds that they discriminate on the basis of race, national origin, and political belief, and that they deprive foreign nationals of due process protections. While the Court has not ruled on religious discrimination, it has also never given the slightest indication that religion would be exempt from the general rule.
There is even precedent for Trump’s plan. In 1891, Congress passed a statute that made inadmissable people who practice polygamy (directed, at the time, at Mormons), and in 1907 extended this ban to people who “who admit their belief in the practice of polygamy.” While Congress later repealed the latter provision (the former seems to be still on the books), no court–as far I know–ruled it unconstitutional.
Plenary power doctrine. Shove that in the face of every cuckservative who blathers ignorantly about the unconstitutionality of Trump’s proposed policy. There is more than a century of precedent demonstrating otherwise. Anyone who says a religious immigration ban is unconstitutional is either ignorant or lying.
Furthermore, the Federalist Papers make it clear that the several States have the ability to pass religious bans as well. And in a MSNBC poll, 92 percent of Americans 18-24 said Trump is not going too far in his proposal to ban all Muslim immigration.
After all, they’re the ones who would have to live with them.