A Muslim registry would be a government-maintained database where people whose country of origin Islam is the dominant political and legal system, or people who identify as adherents to Islam and reside in or are visiting the country maintaining the database. The claimed purpose would be to preventing Muslim terrorism in the host country. It has been repeatedly discussed in the United States following the September 11, 2001 attacks that were carried out by Islamic terrorists. People who oppose such a registry claim that it violates the First Amendment right to freedom of religion. It is to be noted, however, that while it does have religious trappings, Islam is technically more of a political movement than an actual religion.
The problem is divided in two parts, (1) people who enter tbe country (whether legally or illegally) usually on a temporary basis, such as visitors, tourists or students; and (2) those seeking naturalized citizenship status. Ideological tests are as old as US immigration law. Indeed, immigration statutes originated in the 1920s to regulate, and prevent, Bolsheviks and anarchists who advocated the violent overthrow of the United States government from entering the country.
The closest thing to a "Muslim registry" in the United States was a database of immigrant males from so-called "Islamic Republics" created by the Bush administration, shortly after after the 9-11 attacks. The Bush administration created the National Security Entry-Exit Registration System (NSEERS), requiring all males 16 years of age or older visiting from 25 countries to register. Although no religious groups were explicitly targeted, 24 countries had Muslim-majorities; the 25th, North Korea, did not. The countries included: Afghanistan, Algeria, Bahrain, Bangladesh, Egypt, Eritrea, Indonesia, Iran, Iraq, Jordan, Kuwait, Lebanon, Libya, Morocco, Oman, Pakistan, Qatar, Saudi Arabia, Somalia, Sudan, Syria, Tunisia, United Arab Emirates, Yemen. The NSEERS program registered and monitored more than 80,000 men and boys, according to a 2012 report by Penn State Law and Rights Working Group (2 or 3 percent of the US Muslim population). The report stated that more than 13,000 of those registrants were placed in deportation proceedings (around 16 percent).
Non-governmental data sources
It has been claimed that the data is already compiled by Facebook with respect to Muslim Facebook users.
According to Ars Technica:
- Facebook has the data already; the company can provide a list of self-attested Muslims in the US simply by writing a query or two. 
Discussion and controversy
United States citizens who are Muslims were not covered by NSEERS. Neither were the people who carried out domestic terrorism in the United States since September 11, 2001, including the Boston Marathon bombings, the San Bernadino attack, or the Orlando Florida attack.
Naturalization and citizenship
Under current law an applicant who wishes to become a US citizen must be "attached to the principles of the Constitution of the United States, and well disposed to the good order and happiness of the same." The Federal Register states "Attachment implies a depth of conviction which would lead to active support of the Constitution. Attachment and favorable disposition relate to mental attitude, and contemplate the exclusion from citizenship of applicants who are hostile to the basic form of government of the United States, or who disbelieve in the principles of the Constitution." The First Pilar of Islam which states, "There is One God but Allah and Mohammad is his Prophet", under Salafi and Wahhabi teaching, implies Allah is the sovereign lawmaker, and the United States Constitution and United Nations Charter are invalid man-made laws attempting to void Allah's sovereignty.
Therefore, anyone who has completed the naturalization process has been found to have a mental attitude that would not require him to be tracked in a registry, apart from the Constitutional problems of including such citizens in such a registry.
Donald Trump comments
|“|| Does Donald Trump want a registry for all Muslims? Or just some Muslims? Or no database at all?
The Republican presidential candidate’s comments on the topic have drawn a lot of criticism, with some pundits and commentators comparing it with the registration of Jews in in Nazi Germany. But Trump has said he didn’t propose such an idea -- a reporter did, and Trump just didn’t understand the question.
His comments and the media coverage of them have left us confused, so we did a deep dive into what exactly Trump said about registering Muslim people in a database.
After going through all of his comments from this past weekend, it seems that Trump definitely wants a database of Syrian refugees, and he hasn’t ruled out the possibility of a database for all Muslims -- though he isn’t actively calling for the latter. 
Reporters have tried to get Trump or his supporters to go on record as clearly for or against such a registry. Usually the response is to widen the scope of the discussion to ways to prevent foreign terrorists of any stripe from entering the U.S. - rather than creating (as one reporter originally suggested) a registry specifically targeting Muslims.
- Obama ditches registry focused on immigrant men from Muslim countries
- "The Bush-era Muslim registry failed. Yet the US could be trying it again", cnn, December 22, 2016. Retrieved on December 25, 2016.
- "Obama Just Made It Harder for Trump to Create a Muslim Registry", The Atlantic. Retrieved on December 25, 2016.
- "Obama’s team cancels Muslim registry to foil Trump’s ‘extreme vetting’ plans", Washington Times, December 22, 2016. Retrieved on December 25, 2016.
- 8 U.S.C. § 1427(a).
- 8 C.F.R. § 316.11(a) (2009).
- I didn't suggest a database-a reporter did.Twitter 10:51 AM - 20 Nov 2015