The First Amendment was written because Christians of all denominations believed that while people's religious beliefs are the basis for the law, no one Christian group should be supported by the power of the federal government. After all, that's why many Americans had fled England.

Americans are having a hard time discussing the problem of Muslim immigration and assimilation because Islam is not just a religion; it's a whole way of life, civil and spiritual.

Islam, according to many Muslims, rejects that principle and declares that all authority belongs to Islam. It's as though Catholics believed that the pope should be the ultimate authority for setting the fine you have to pay if you get a speeding ticket.

It's important to note that it doesn't matter what Islam "really teaches" so long as there are a lot of Muslims who say Islam supports theocracy and terrorism. We have to deal with reality, not some hypothetical "pure" Islam.

Because Islam demands Muslims' full civil as well as spiritual assent, it's fundamentally different from any faith that Americans are truly familiar with – which makes discussing it difficult. Is someone saying we should reject Muslim immigrants because of their religion, as Americans understand it, or because some Muslims believe that the Constitution must bow before the Quran, or because some Muslims believe that violence can be used in honor killings and to avenge insults against Mohammad?

While it's true that the majority of American Muslims are quite comfortable with the Constitution, the reality is that Islam lays claim to worldly authority in every nation. That means that it's possible to reject Muslim immigrants not because of their faith, but because it's not irrational to assume that the first civil loyalty of at least some Muslims, especially those from Muslim-majority countries, is to Islam, not the Constitution.

The current Muslim situation is not the first time America has been concerned with immigrants because of their faith. Historically, America discriminated against Catholics and Catholic immigration because many Protestants erroneously believed that Catholics wanted to establish a theocracy in America. Many laws with a religious test resulted from that concern.

But unlike the baseless scare over something the Catholic Church did not teach – namely, that the pope should be running America – Islam does teach, at the very least in the minds of many Muslims, that all countries should be theocracies. If anyone doubts that a large fraction of Muslims believe that Islam calls for sharia law, one only has to look at how things are run in most Muslim-majority countries. One can look in vain for all the Catholic-majority countries run by the pope or his bishops.

Pakistan is nominally a democracy with religious freedom, but non-Muslims can be killed for preaching their faith – hardly compatible with the American view of religious liberty. On the other hand, Ireland legalized so called same-sex marriage – hardly an indication of Catholic theocracy.

The critical question is, what fraction of Muslims who wish to come to America reject the idea that their first civil loyalty is to Islam? It's hard to tell, since there seems to be a dearth of polling of American Muslims where they are asked about sharia law. But according to a Pew survey, support for sharia law is fairly common among Muslims in a wide variety of countries.

For the first time in its history, America is facing the question of how to deal with people whose religion is often interpreted by many of its adherents, as opposed to its detractors, to reject the principles of democracy and religious liberty.

With nearly 3,000,000 Muslims in America and a major terror attack requiring the support of only a handful of people, it doesn't take a large percentage of radicals to create serious problems.

In the end, the real question – considering that whenever and wherever Muslims have a chance, at least some of them try to institute sharia law, even if only for Muslims, and considering the widespread belief that advancing Islam justifies terrorism – is, is it reasonable to let a lot of poorly educated hardcore Muslims into the U.S.? Even if Islam does not teach that a Muslim's first civil loyalty is to Islam, the reality is that it appears that a lot of Muslims think that it does. Contrary to liberal beliefs, America is not strengthened by bringing in people who disagree with our founding principles.

Most Americans support the commonsense solution of differentiating between radical Muslims and those Muslims who can accept the Constitution instead of sharia law. Liberals, however, are causing controversy by condemning Christians for crimes of the ancient past while ignoring real issues with Islam.

Liberals have a strong incentive to ignore Islamic extremists because Muslims in America tend to be Democrats (70%) and not Republicans (11%). However, it is strange, if one assumes that liberals are trying to be coherent, that the same liberals who condemn Christianity because of the Crusades, defensive wars designed to free Christians from Islamic oppression that occurred centuries ago, become strangely silent in the face of modern radical Islam.

It's odd that liberals who tar all Christians for the crimes of one nutcase who attacked Planned Parenthood are unwilling to admit that some terrorists are inspired by the writings of a fanatical conqueror who advocated slaughter of those who opposed him and who married a six-year-old girl.

Saying we are at war with those who have an extremist view of Islam and not with all those Muslims, and there are a lot, who don't believe in the use of violence to spread Mohammad's heresy seems to make excellent sense, yet liberals reject associating Islam with people who say they are killing in the name of Islam and who can cite chapter and verse where the Quran supports them.

Perhaps we could have a better national dialog if liberals didn't ban Christian refugees while ignoring the potential problem associated with bringing in Muslims, whose faith may lead them to put Islam ahead of America on civil matters. That doesn't mean we have to ban Muslim immigration, and it certainly doesn't mean we should condemn all Muslims, but it does mean we should have a plan in place to ensure that the Muslims we let in share our view of civil authority vis-à-vis religious authority.

While liberals are right when they say that declaring that all Muslims, especially all American Muslims, are evil is playing into the hands of extremists, it's also wrong to simply ignore the links between Islam and terrorism and the fundamentally different natures of Christianity and Islam. We can't be safe if we bury our heads in the sand and ignore the root cause of Islamic terrorism.

You can read more of Tom's rants at his blog, Conversations about the obvious. Feel free to follow him on Twitter.