Religion and freedom of religion is protected only for CITIZENS of the United States, not immigrants or those attempting to immigrate. So, number 1....those who argue this against Trump lose because they are NOT here, and are not subject to protection under the constitution.
Naturalization is widely covered by the Constitution...who is considered a citizen, and how those who wish to become citizens, do so. I don't even know why I am playing this game but why not.
Article 4 section 4 also give the government the power to protect states from invasion. A complicated law and interpretation, highly debated as well...and as you may know the center of the Jan Brewer and the State of Arizona's lawsuit with the US government.
Invasion is a very broad stroke, and can be from neighboring states, countries and or governments.
Here is a link to maybe help you better understand why Obama is fighting this Article so hard as he wants as many illegals on the streets as possible.
http://www.wnd.com/2013/03/lawmakers-told-constitution-requires-secure-border/
Here is a quote if you don't feel like reading the whole story.
ABC says it might be “an impeachable offense for the commander in chief to disobey this clear and unequivocal command of the U.S. Constitution.”
In the letters to lawmakers, ABC says: “Border incursions by violent drug smugglers and other criminals is the primary issue here. To protect against these criminals, the U.S. government is constitutionally required to secure Arizona’s borders (for all purposes).”
In fact, as part of a ratification to this Article, ALL FEDERAL OFFICIALS take an oath to uphold the constitution, and the oath deals specifically with this Article 4, section 4.
"I, [name], do solemnly swear (or affirm) that I will support and defend the Constitution of the United States against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; that I take this obligation freely, without any mental reservation or purpose of evasion; and that I will well and faithfully discharge the duties of the office on which I am about to enter." (33 U.S.C. § 3331.) By federal statute, all state officers shall take an oath in the simple form first promulgated in 1789. (4 U.S.C. § 101.)
So, do I need to extrapolate any further?
Banning all Muslims based on religion? Mehhh...a little dicey.
Banning all groups of people from countries that are state sponsors of terror from entering our country? Hell yes, protected by the constitution.