Apparently, there is nothing Donald Trump can say that is so outrageous that you will not find a right-wing apologist willing to defend it. Case in point: his call for a ban on allowing Muslims to enter the United States. The idea itself is abhorrent to me, and goes against everything we stand for and believe in as Americans. And when that's what Dick freaking Chaney is saying about your plan, you really have gone off into the wilds of reactionary lunacy. So, naturally, justifications for Trump's remarks have started showing up in my Facebook feed.
The one I've seen the most often, probably because it's the one that pretends to almost make an attempt at avoiding blanket bigotry, is one that goes like this: "Donald Trump's proposed ban on Muslims is just like Jimmy Carter's actual ban on Iranians." Actually, Trump's proposed ban on Muslims is almost completely unlike Jimmy Carter's actual ban on Iranians. Here's why:
Iran is a country. Islam is a religion. Those are two very different things, particularly when it comes to things like international law.
It is absolutely a fact that Jimmy Carter issued orders barring Iranians from entering the US during the Iran hostage crisis. (Of course, it's also true that Carter's order contained an exception for "compelling and proven humanitarian reasons," while the frothing Islamophobia spewing forth from even the more respectably mainstream portions of the American political right - such as the elected government of the State of Texas - seems to be largely directed at keeping Muslims with "compelling and proven humanitarian reasons" to flee their homes from entering the USA, but let's put that issue to the side for now.)
During the Iran hostage crisis, the US Embassy was taken over and US citizens were held hostage. The new government of Iran was refusing to return the hostages to the US, despite (by the time of Carter's declaration) an order from the International Court of Justice. (By the way, the Frontpage article I linked earlier asserts that "Khomeini didn't represent Iran as a country," but this is legally incorrect - the ICJ in fact found otherwise in their final order in the case.) Carter's acts were not taken against a religion; they were part of a series of steps taken by a nation against another nation during an international crisis.
Carter's ban on Iranian entry to the US was one of several parts of the same order. The other measures included breaking off remaining diplomatic relations, imposing a ban on exports to Iran, and beginning to inventory Iranian assets in the USA (which had already been frozen). These are all fairly common trade embargo measures; trade embargoes have been one of the more common ways that nation-to-nation disputes play out for centuries.
A blanket ban against members of a particular religion, on the other hand, is not a typical part of national conflicts. Even if it is legally possible under US law to ban Muslims from entering the United States, it would violate any number of international obligations, including some that could easily lead to the US having to pay monetary damages.
Barring citizens of a specific nation from entering the US at a time when we are at or near a state of war with that country: morally and legally acceptable. Barring 1.6 billion people from an enormous number of countries from entering the United States because they nominally share a religion with terrorists: not morally acceptable, not legally permissible, and bloody stupid by any reasonable definition.