"Religious freedom and national security overlap," Farr stressed. "Advancing religious freedom abroad will increase U.S. national security by undermining religious extremism. The Obama administration sometimes gives lip service to that very important connection, but they have utterly failed to do anything about it."
Supporters of Trump argue that the measure may be necessary for national security. FBI Director James Comey recently warned that there are at least 900 active ongoing investigations of ISIS terrorist plots with suspects in all 50 states.
"Muslims should not be prohibited from entering the United States on a permanent basis but temporarily until the government gets its act together. No foreigner has a constitutional right to come to America," said Jeffrey Lord, a CNN commentator and author of "What America Needs: The Case for Trump."
"We need to fix our faulty government system that is allowing terrorists like Tashfeen Malik in," he told CNA. "People should not go to an office party and then be shot senselessly and die. Trump's policy simply makes sense and is not anti-immigrant."
"All the signs were there with Malik and the Fort Hood shooter, but political correctness stood in the way of properly investigating these people," said Lord, who formerly served as Ronald Reagan's White House political director. "Now, many innocent Americans are dead."
Trump's proposed policy does have legal precedent. After the 1941 attack on Pearl Harbor by the Japanese Navy, President Franklin D. Roosevelt passed several executive actions which prevented German, Japanese and Italian citizens from immigrating or traveling to America. The measures also authorized the surveillance of those allowed to remain in the United States.
The U.S. Supreme Court has affirmed the plenary power of Congress to regulate immigration. In 1973, it ruled in Kleindienst v. Mandel that the U.S. Attorney General has the right to refuse a person entry into the United States under the Immigration and Nationality Act of 1952.
In that case, Dr. Ernest Mandel, a citizen of Belgium and a renowned Marxist scholar and journalist, was seeking a visa to speak at conferences and schools in the United States. He was denied entry under immigration law regarding "aliens who write or publish . . . the economic, international, and governmental doctrines of world communism or the establishment in the United States of a totalitarian dictatorship."
According to the Supreme Court's decision in Kleindienst v. Mandel, "the power to exclude aliens is 'inherent in sovereignty, necessary for maintaining normal international relations and defending the country against foreign encroachments and dangers--a power to be exercised exclusively by the political branches of government . . . .'"
Howsoever, Kacsmaryk noted that while "the Supreme Court has repeatedly affirmed the 'plenary power' of Congress to regulate immigration, it has never affirmed the categorical exclusion of persons based on religion."
"Because religion lies at the heart of the First Amendment Free Exercise and Establishment Clauses and is a protected class under several federal statutes, Congress should focus its immigration firepower on non-religious criteria that more closely correlate to terrorism," he said.
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In addition to banning Muslims entry into the United States, Trump is in favor of monitoring and closing down mosques with suspicious activities. There are more than 2,000 mosques in the country, most of which have been built in the last 30 years, according to a survey by Faith Communities Today.
"Nobody wants to say this and nobody wants to shut down religious institutions or anything, but you know, you understand it. A lot of people understand it. We're going to have no choice," Trump said in an interview on Fox News' "Hannity" on Dec. 17.
"This is not about religious freedom, said Lord. "The FBI has investigated the Catholic Church during the pedophile scandal, as well as Protestant evangelicals for money laundering, and Jewish groups for illegal activity."
"The U.S. government can investigate religious activists if they are breaking the law or there is a threat. In the 1950s, the FBI investigated the Italian mob and monitored Italian Americans," said Lord. "You go where the problem is. You don't say the mob is Italian so let's investigate the Amish. You also don't ignore a problem for fear of being called anti-immigrant."
However, religious liberty advocates have warned that the measure could have a chilling effect on religious freedom in the country. They noted that the tables could easily be turned and another religion could find itself the subject of such scrutiny.
"In principle, why not?" said Catholic University of America associate professor of theology Joseph Capizzi. "Once the government determines to screen people by religious affiliation – and not just by any religious affiliation, but one with over 1000 years of belief and practice and a billion or so followers, by what principle could it distinguish that faith from any other?"