A surprising number of students who enter my world religions classes every semester seem to have the idea that the United States is a “Christian nation.”

It isn’t.

Now, we must of course be careful to clearly define our terms here. If we are simply talking about population statistics, then it is certainly true that the vast majority of the U.S. populace does indeed self-identify as Christian. (A recent Pew Forum survey indicates that the national American adult population is in fact over 78% Christian.)

However, if we are talking about the American system of government itself — its nature, its basis, its principles, its character, its policies — then it is quite clear (or at least it should be) that the United States is a secular republic, and by no means an officially “Christian nation,” per se.

Contrary to what seems to be a fairly widespread popular belief, the fundamental and guiding basis of American government as a whole is not the Bible, but the U.S. Constitution.

And the U.S. Constitution is a thoroughly secular document. Anyone who takes the time to read it all the way through will find that neither God nor Jesus are mentioned anywhere within it. And “secular” simply means that religion and government are to be kept independent of each other. Thus the First Amendment to the Constitution (itself part of the Bill of Rights) clearly states that “Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof.”

To drive the point home even further, American Founding Father and second U.S. President John Adams is on record as having explicitly stated that “the Government of the United States of America is not, in any sense, founded on the Christian religion.”

And, while the actual phrase “separation of church and state” may not appear verbatim within the Constitution itself, it was made abundantly clear by Founding Father and third U.S. President Thomas Jefferson that this is in fact the guiding principle behind the First Amendment. Jefferson is on record as having explicitly stated that since “religion is a matter which lies solely between Man & his God… I contemplate with sovereign reverence that act of the whole American people which declared that their legislature should ‘make no law respecting an establishment of religion, or prohibiting the free exercise thereof,’ thus building a wall of separation between Church and State.”

That “wall of separation” means that the U.S. government is not to interfere with religion, and by the same token religion (religious beliefs, religious practices, religious principles) cannot be utilized as a valid basis for U.S. laws or government policies. The state can neither support nor suppress religion in America; it can neither favor one religion over another, nor favor religion over irreligion (or vice versa). Rather, the state must remain officially neutral regarding religious matters, thereby guaranteeing fair, unbiased, and equal treatment for citizens of every religion (and of no religion).

This secular “wall” is thus the essential foundation for the freedom of religion which U.S. citizens enjoy. The United States is even historically noteworthy in this regard, because in establishing the U.S., its Founding Fathers thereby established the world’s first such fully secular nation. It’s somewhat alarming that a sizable percentage of the American public today seems less than fully cognizant of all of this, imagining instead that the U.S. is somehow built upon explicitly Christian or biblical principles. It just ain’t so.

It’s also somewhat alarming — or at least it is to those who understand and support the Constitutional principle of separation of church and state — to see this principle violated, or to see that wall eroded, whenever misguided politicians (who really should know better) support clearly unconstitutional policies or seek to impose unconstitutional laws that favor one specific religion over another, or that favor religion in general over nonreligion.