I’ve been going back to the sources to try to discover whether the religious tolerance of the American Founders would or should extend to extremist Islamist preaching. Even in a tolerant society, not all things are or should be tolerated. You have freedom of speech, but you can’t shout “fire” in a crowded theater.

Freedom of religion — or liberty of conscience to give it its broadest name — seems to admit very few exceptions. An astonishing range of religions thrive among us, from Santaria to Southern Baptism. In the name of liberty of conscience we tolerate religions that require their followers to surrender liberty of conscience and follow a preacher or a book.

But what about Islamist religion, which preaches identification with the worldwide Muslim ummah rather than local civic society, which sets religious authority above any secular state power, and which has a long-term goal of plowing under Western freedoms, including liberty of conscience, into shari’a law? Such things existed in the world in the 18th century, but the Founders never addressed them.

America is not re-invented every generation, despite the appearance, and it has underpinnings in certain currents of philosophy and the thoughts of specific men. Yet to discuss the Founders as a guide to present policy seems anathema to many otherwise thoughtful people; as if to accept the relevance of Madison and Jefferson is to accept their whole vision of America. To less thoughtful Americans, I think, our past is a dead land, populated by monstrous slave-owning philosophes and Indian-killers and sexually repressed Puritans.

John Locke’s “Letter Concerning Toleration” is the philosophical foundation of the American separation of church and state, religious equality and freedom of conscience — key elements of the Western pantheon, and hateful poisons to its Islamist enemies.

When it comes to religion, Locke politely tells the political authorites to butt out. He enjoins the would-be religious meddlers:

If any man err from the right way, it is his own misfortune, no injury to thee; nor therefore art thou to punish him in the things of this life because thou supposest he will be miserable in that which is to come. Nobody, therefore, in fine, neither single persons nor churches, nay, nor even commonwealths, have any just title to invade the civil rights and worldly goods of each other upon pretence of religion.

Locke mainly was concerned with mutual toleration among Christians in England. But he extended this philosophy beyond the Christian churches. Even pagans, who in his day would have been regarded with abhorrence, came in for the hands-off treatment.

But, indeed, if any people congregated upon account of religion should be desirous to sacrifice a calf, I deny that that ought to be prohibited by a law. Meliboeus, whose calf it is, may lawfully kill his calf at home, and burn any part of it that he thinks fit. For no injury is thereby done to any one, no prejudice to another man’s goods. And for the same reason he may kill his calf also in a religious meeting. Whether the doing so be well-pleasing to God or no, it is their part to consider that do it. The part of the magistrate is only to take care that the commonwealth receive no prejudice, and that there be no injury done to any man, either in life or estate.

Locke wrote at the close of a generation rent by a civil war and a revolution, and in a century when the clash of Crown and Parliament and the overlapping conflicts between Protestants, Anglicans and Catholics, bloodied England.

Locke’s “toleration,” however, was not universal. It expressly excluded atheists, because, as is still commonly believed, they had no motive to be moral and therefore could not be trusted to be so. And Locke’s toleration, like John Milton’s, excluded Catholics, who, at that time, acknowledged the authority of a Pope who was prince of a secular realm, and a power-rival and dangerous enemy of the ruler of Britain.

And it certainly would have excluded the type of religion preached in modern Britain by Islamist imams. Locke excludes the intolerant from his toleration (a needle’s eye that probably excludes many modern Christian fundamentalists as well).

These, therefore, and the like, who attribute unto the faithful, religious, and orthodox, that is, in plain terms, unto themselves, any peculiar privilege or power above other mortals, in civil concernments; or who upon pretence of religion do challenge any manner of authority over such as are not associated with them in their ecclesiastical communion, I say these have no right to be tolerated by the magistrate; as neither those that will not own and teach the duty of tolerating all men in matters of mere religion. For what do all these and the like doctrines signify, but that they may and are ready upon any occasion to seize the Government and possess themselves of the estates and fortunes of their fellow subjects; and that they only ask leave to be tolerated by the magistrate so long until they find themselves strong enough to effect it?

In America a century later, James Madison took Locke one step further. Madison scholar Robert Alley writes that, “toleration presumed a state perogative that, for Madison, did not exist.” Madison wrote that “the right to tolerate religion presumes the right to persecute it.” Instead Madison argued for “liberty of conscience.” The “natural rights of man,” centering in the concept of “liberty of conscience,” stand, without question for Madison, above and before any other authority.

No religion, or irreligion, can be banned by the state. Even religions that make it a central aim to overthrow the state (up until the point where they act in that aim).

When Madison took his place in the Virginia legislature after the Revolutionary War, a bill stood in the General Assessment, sponsored by Patrick Henry, that would funnel tax money to support religious education in all denominations.

Henry justified this as a way to curtail the sin and immorality of young people. But the General Assessment bill would have hatched the monster Madison feared most: a “tyranny of the majority.” If the ministers from all the major Protestant denominations were paid from the state treasury, a coalition of Protestant groups would relegate minority views to a “tolerated” status or worse.

The legislature was on the verge of passing the bill, but Madison convinced his colleagues to postpone a vote until the next session in 1785. Madison used the postponement to take his case to the public, writing a broadside critique, the “Memorial and Remonstrance Against Religious Assessments,” which has become the classic statement for religious freedom in North America.

I cannot find that Madison, here or anywhere else, made exceptions, as Locke did, to what the state ought to tolerate in the way of religion. His sole concern was protecting the individual conscience from the intrusion of state power.

The Religion then of every man must be left to the conviction and conscience of every man; and it is the right of every man to exercise it as these may dictate. This right is in its nature an unalienable right. It is unalienable, because the opinions of men, depending only on the evidence contemplated by their own minds cannot follow the dictates of other men: It is unalienable also, because what is here a right towards men, is a duty towards the Creator. It is the duty of every man to render to the Creator such homage and such only as he believes to be acceptable to him. This duty is precedent, both in order of time and in degree of obligation, to the claims of Civil Society.

Madison insisted government keep its hands absolutely off religion.

Before any man can be considered as a member of Civil Society, he must be considered as a subject of the Governour of the Universe: And if a member of Civil Society, do it with a saving of his allegiance to the Universal Sovereign. We maintain therefore that in matters of Religion, no man’s right is abridged by the institution of Civil Society and that Religion is wholly exempt from its cognizance.

Madison, it seems, took no cognizance of what Karl Popper, in a later, darker century than the 18th, would describe as the “paradox of tolerance.�

Unlimited tolerance must lead to the disappearance of tolerance. If we extend unlimited tolerance even to those who are intolerant, if we are not prepared to defend a tolerant society against the onslaught of the intolerant, then the tolerant will be destroyed, and tolerance with them.

In this formulation, I do not imply, for instance, that we should always suppress the utterance of intolerant philosophies; as long as we can counter them by rational argument and keep them in check by public opinion, suppression would certainly be unwise. But we should claim the right to suppress them if necessary even by force; for it may easily turn out that they are not prepared to meet us on the level of rational argument, but begin by denouncing all argument; they may forbid their followers to listen to rational argument, because it is deceptive, and teach them to answer arguments by the use of their fists or pistols.

We should therefore claim, in the name of tolerance, the right not to tolerate the intolerant. We should claim that any movement preaching intolerance places itself outside the law, and we should consider incitement to intolerance and persecution as criminal, in the same way as we should consider incitement to murder, or to kidnapping, or to the revival of the slave trade as criminal.

UPDATE: Botched the Popper quote the first time. Sorry about that. Fixed now.