> He has said that a judge of Mexican descent couldn’t treat him fairly because of his heritage

No, that is what much of the media wants to claim, say, for clicks.

Instead, there are two points where can use because. The first point is, Trump asserts that the judge is unfair, and Trump asserts this because of the judge's rulings. The assertion of unfairness is from the rulings with nothing to do with Mexico. Second, as in

https://www.youtube.com/watch?v=CWKmpB7SeNE

with

> All I'm trying to do is figure out why
I'm being treated so unfairly by a judge.
And a lot of people agree with it. All I
want to do, all I want to do is find out
why I'm being treated so unfairly by a
judge.

Trump was looking for the MOTIVATION of the judge to be unfair. Then it was easy enough to notice that the judge has a Mexican background and is active in some pro-Mexican political causes that conflict with some of Trump's campaign positions on Mexico. So, Trump concluded that the judge's MOTIVATION to be unfair was because of the Mexican stuff.

Trump asserted unfairness because of the RULINGS with nothing about Mexico.
Then, as a second step, Trump asserted that the
judge was MOTIVATED to be unfair because of the Mexico stuff.

So, we have two points and two uses of because. But much of the media, in their search for clicks, conflated those two to assert that Trump said that the judge was unfair because of the Mexican stuff. Nope: That would be poor evidence that the judge had been unfair. Instead, the claim that the judge was unfair was because of the judge's RULINGS. Then, the MOTIVATION for that unfairness was because of the Mexican stuff.

In no way did Trump assert that all judges with Mexican backgrounds would be unfair, but much of the media wanted to play with words to conclude that.

The US has, IMHO rightly, decided that racism is a bad thing. Sure, long in the US, people of Western European descent were racist against Native Americans, Africans, Irish, Italians, Asians, Jews, and Mexicans. Well, the US has gone a long way to stopping that. But neither do we want Native Americans, ..., etc. to be racist against others, e.g., persons of Western European descent. We want no racism, from anywhere.

> Freedom of religion is a constitutionally protected right. I don't see how this right can be protected if you filter possible future citizens based on religion.

There are at least three really big problems with your statement here:

First, the US gets to decide who can enter the country and for that decision can use any reasons or no reasons. Non US citizens outside the US have no "rights" in the US at all. The US gets to run its immigration system in any way it wants.

Second, Islam is a long way from being just a religion. In addition to religion, Islam runs marriages, dress codes, lots of social norms, diets, education, architecture, media, the legal system, foreign policy, government, and, yes, also religion. Each part of Islam regards everyone else as an infidel to be either converted to killed. In this way, the Sunni and Shiite parts of Islam have been at war for 1000+ years, and recent examples include the Iran-Iraq war, the Baghdad-ISIS war, the Syrian civil war, and the high tension between Saudi Arabia and Iran, e.g., in Yemen. Islamic religious leaders issue Fatwahs, commands, calling for Jihad, holy war. ISIS has declared war on Europe and the US. Iran says "Death to America", and that cry is also common in parts of Pakistan. Net, when considering immigrants to the US, Islam must be regarded as not nearly just a religion.

Third, the Islamic immigration under most consideration now is heavily from areas of the Mideast awash in Islamic wars and violent Medieval Islamic culture, indeed, from areas that have declared war on the US. And that immigration is not via the usual legal channels but for "refugees". From the list of violent attacks from radical Islamic terrorists in the US, Europe, etc., the "refugees" are an obvious threat to the US. So, no way should the US admit such people. And, even if the wars end, it is in the strong interests of the US to reject people who likely will not assimilate. E.g., the US does not want whole communities that reject much of US culture and, instead, are devoted politically to religious leaders and follow Sharia law -- not in the interests of the US.

But, a Muslim US citizen has full US citizenship rights as you suggest.