While the app that I published to Google Play on New Year's Eve does indeed specifically refer to the Bible in its description and strings, it should be noted that the Bible is not the only document out there that the method that this app educates on is applicable to. An example of a piece of another document that was misquoted was the Ninth Circuit case Washington v. Trump, in which the people making the ruling ruled, while completely ignorant of context and of other laws, that President Donald Trump's travel ban on certain Muslim-majority countries violates the Establishment Clause, in spite of the fact that the Constitution was written for citizens, not for aliens. They should have thought about it further by thinking the same way that I, at least, think about the Bible — that is, by application of exegesis to the Constitution.
What is the situation or setting of the Establishment Clause? It's 1790 in the brand-new United States of America. Having been fed up with how hypocritical the Church of England has been with them, stifling the freedoms of Jews and of other sects of Christianity, the Founding Fathers had decided that enough is enough, and decided that the federal government should not give one church or synagogue official favor over any other. Were there Muslims in early America? Perhaps as slaves, but slaves were not US citizens until 1868. Did the Founding Fathers intend to give resident aliens constitutional rights? Per the Alien and Sedition Acts, supported by many of the Constitution's authors, the answer to that would be "No".
The type of literature that the Establishment Clause conveys, meanwhile, is obvious: a statement expressly forbidding the government from exercising a power that other governments at the time exercised on a regular basis. The Establishment Clause's object is, of course, whether or not the federal government should make one religion or sect thereof the official religion and outlaw all the others, and the prescription of the Establishment Clause is that the government refrain from doing the above. Does a restriction on immigration from certain parts of the world have anything to do with literally establishing an official religion for the United States, which is the only act — the ONLY act — that the Establishment Clause condemns? No. US citizens can still choose whatever religion they want to regardless.
So, in the original context, no, the Establishment Clause is not applicable to aliens, no, it is not applicable to foreign tourists, and no, it is definitely not applicable to those who overstay their visas or cross borders without proper documentation, breaking US immigration laws in the process. Only citizens have Establishment Clause protection, and anyone who rules otherwise is quote mining the Constitution in a manner that people like Neil Gorsuch and Antonin Scalia are/were sternly, vehemently opposed to. The judicial branch is the judicial branch. It was never intended to and is never supposed to have legislative power. Judicial activism is a total usurpation of the separation of powers as prescribed by the Constitution of the United States and is therefore an unconstitutional mindset in itself.