IN THE year of our Lord 1816 two grand old men of the American Revolution corresponded eagerly about the work they had recently done, in their rural retirement, on the Bible. Ex-President Thomas Jefferson thanked his old friend Charles Thomson, a co-sponsor of the Declaration of Independence, for sending a copy of his newly completed synopsis of the Gospels.

At a time when many modern Americans are arguing feverishly over the real significance of the nation's religious and political beginnings, such letters can be dynamite. So let the contents of this exchange be noted carefully. Thomson, like most members of the first American Congress, which he had served as secretary, was a committed member of a church—in his case Presbyterian—but he still felt that there might be things in the Bible that organised Christianity hadn't grasped. So he spent years re-translating the scriptures; the ex-president approved.

But Jefferson, like most of the top figures in the American Revolution, was far more of a sceptic in religious matters. He was fascinated by metaphysics but he had no time for the mystical. In contrast with today's vituperative exchanges, these differences did not stop the two gentlemen maintaining a warm correspondence. But Jefferson's approach to redacting the Bible involved something more radical than translation. He literally snipped out everything supernatural: miracles, the Virgin birth, the resurrection. The result was his own, non-mystical account of the life of Jesus. He told his old comrade: “I too have made a wee little book from the same materials which I call the ‘Philosophy of Jesus.' It is a paradigma [sic] of his doctrines, made by cutting the pages out of the book and arranging them on the pages of a blank book…A more beautiful or precious morsel…I have never seen. It is a document in proof that I am a real Christian, that is to say, a disciple of the doctrines of Jesus, very different from the Platonists who call me infidel and themselves Christians.”

If Jefferson was a Christian of any kind, he was an idiosyncratic one. He admired Jesus as a moral teacher but like many of America's revolutionaries, he had a visceral loathing for priestcraft. Jefferson blamed Saint Paul, the early Church, and even the Gospel writers for distorting the mission of Jesus, which, as he saw it, had been to reverse the decadence of the Jewish religion. Starting from the (correct) proposition that mystical ideas originating from Plato were influential when Christian theology was being developed, he castigated followers of the Greek philosopher for corrupting what he saw as the original Christian message.

Did Jefferson believe in God? Certainly not the Christian idea of a God in three Persons; he saw that notion as incomprehensible and therefore impossible for a rational person to accept. One view is that like many of America's founders, he was a Deist, believing in a Creator who set the universe and its laws in motion but did not intervene thereafter. (The Deist God has been described as rather like a rich aunt in Australia—benevolent, a long way off, and mostly leaving the world to its own devices.)

The shape of the Earth, for example, he ascribed to a Creator's genius. “Had He created the Earth perfectly spherical, its axis might have been perpetually shifting by the influence of the other bodies of the system,” Jefferson once told Thomson. Others think Jefferson's views were somewhere between Deism and traditional Theism. In language that some modern American conservatives can pounce on, he once asked whether the young republic's liberties could be secure without “a conviction in the minds of the people that these liberties are a gift from God”. But that does not imply he held such convictions. Although we know what Jefferson did not believe, it is harder to say what he did believe.

Between now and the 2012 presidential election, many pronouncements by the founding fathers—especially but not only on the subject of Christianity—will be parsed and dissected with passion by both sides. Liberals, keen to protect the American variety of secularism from what they see as a resurgence of zealotry, will stress the rationalist leanings of most of the revolution's protagonists; religious conservatives will point out that the revolution's foot-soldiers were generally people of faith who would be shocked, for example, by the idea of banning prayer in schools.

Believers in the idea that America was established as a Christian state scored a hit last year when the Texas school board, a politicised body in which evangelicals control crucial votes, ordered up textbooks laying out this view. Given the size of the Texan market, school-book publishers across the country often follow its lead. The best-known advocate of the “Christian nation” theory is a Texan, an author and evangelist called David Barton, who has been writing on the subject since the 1980s.

Among his recent claims are that the founding fathers rejected Darwinism (although they pre-dated Charles Darwin), and that they broke away from Britain in order to abolish slavery. In fact the southern states only joined the Revolution on the understanding that slavery would not be questioned. Strange as his views may sound to most scholars, Mr Barton's philosophy is taken seriously in Republican circles. When Rick Perry, the Texas governor and presidential candidate, held a day of prayer for the nation in August, Mr Barton was an acknowledged endorser. One of Mr Barton's admirers is Newt Gingrich, the former House speaker who argues that American history has been distorted by secular historians to play down the role of faith. “I never listen to David Barton without learning a whole lot of new things,” Mr Gingrich has said.

It is easy to see why politicians are attracted by the assertion that America was founded as a Christian land, and is hence called to be a place of exceptional virtue. It elegantly fuses two beliefs: Christianity itself, and belief in American history as another sacred narrative, one that sees the founders as people of near-infallible wisdom and virtue waging a noble war against the forces of darkness.

If Mitt Romney, a Mormon, and Mr Gingrich confirm their place as front-runners for the Republican nomination, debates over sacred texts and stories—from the Book of Mormon to the days of prayer and fasting decreed by the first Congress—could take some unpredictable turns, even if Mr Romney tries to avoid them. As a political slogan, citing the founders (to condemn welfare, as Mr Perry does) is a formidable weapon; invoking Jesus Christ (to make the case against the minimum wage, as Mr Barton does) is even stronger medicine. Arguments that use both sources at once can seem almost irresistible.

Academic historians are bemused at times by the inquiries they get from people with no previous interest in the nation's beginnings: what did America's creators really believe? Jill Lepore, a Harvard professor who deconstructs the uses and abuses of the past, is wary of would-be historians with an agenda. For her, the founders' genius lay in their willingness to cast doubt on fixed ways of thinking inherited from the past. So to make them final arbiters is to traduce their spirit. Nor, indeed, were the fathers of one mind. They did not spend their time producing pearls of unanimously agreed wisdom. They quarrelled bitterly. Indeed, if something about this period still resonates in modern politics, it may be the fathers' disputes, and the subtle points each side brought to bear. The tug-of-war between Alexander Hamilton, who successfully campaigned for an American central bank and other federal authorities, and Jefferson, who favoured states' rights, is in many ways still going on. Linda Bilmes, a public policy professor at Harvard, sees in Hamilton's argument a practical application of the metaphysical belief that man is neither utterly wicked nor naturally virtuous; it followed, Hamilton thought, that honest, competent administration was needed to maximise the chances of virtue prevailing.

The founders' genius lay in their willingness to cast doubt on fixed ways of thinking inherited from the past. To make them final arbiters is to traduce their spiritJefferson might disagree, but he would enjoy the ensuing debate.

Above all, the fathers were pragmatists. The exigencies of war with Britain, and survival in an unconquered frontier, gave them little choice. Take George Washington. Unlike Jefferson, Washington does not seem to have had much personal interest in matters philosophical. He was a general and politician, not a theologian. Still, when exhorting troops before battle, or addressing fellow citizens of the republic, he could use religious rhetoric. “No people can be bound to acknowledge the invisible hand, which conducts the affairs of men, more than the people of the United States,” he declared in his inaugural address. But these circumlocutions were typical of his references to God.

As his biographer Ron Chernow observes, Washington spoke of “Destiny” or the “author of our being” or simply “Heaven”. Another favourite term was “Providence”—a word often used by Freemasons, a movement of which Washington was an active member. For those who know where to look, the Washington home at Mount Vernon is full of Masonic symbols, one Masonic researcher has written. But on this matter, Ms Lepore cautions against over-interpretation: the Masons were just one of the gentlemen's clubs where squires liked to gather.

Virtually absent from Washington's pronouncements was any reference to Jesus. He did not take communion—for most Christians, the most important rite of their faith—and he did not summon a Christian minister to his death bed. Was Jefferson right, then, to claim that “[Washington] thinks it right to keep up appearances but is an unbeliever”? Washington was certainly a diplomat. Although he remained formally Anglican, as president he wrote friendly letters to many Christian and Jewish communities and attended their services. And when he needed a job done on the estate, he was firm, for his time, about the irrelevance of religion: “If they are good workmen,” he said, “they may be Mahometans, Jews or Christian of any sect, or they may be atheists.”

As every American youngster has been taught, one thing that Washington, Jefferson and all the founders did believe in was religious freedom. They were appalled by the fusion of religious and political power, epitomised by the divine right of kings.

The emphasis on freedom seems clearer than anything else about the founding texts. People may still argue over whether those texts have any religious inspiration at all. The constitution contains little reference to any deity, while the Declaration of Independence appeals to “Nature's God”—a formula that sounds more Deistic than Christian. But the constitution's first amendment seems crystal-clear on the subject of freedom: it bars Congress from establishing any religion, or from erecting any barrier to the free exercise of religion.

Yet for all the sonorous beauty of much early American writing on the subject, religious liberty too should be seen as something pragmatic—a hard-nosed solution to the problem of stitching together a country out of 13 colonies with diverse populations and different religious arrangements. Nine colonies had established churches at the time of the Revolution; most of these regimes sputtered on for several decades afterwards. The religious scene in the colonies ranged from the strict Puritan communities of New England to the suffocating Anglican regime of Virginia. In New England, Anglican clergy acted as fifth columnists for the crown; Virginia had an Anglican American culture of its own. Maryland had always been a comfortable place for Catholics.

It was all a big, volatile mess, to which a regime of religious liberty was the best solution. Among the many impulses behind the Revolution was a network of Presbyterians and other non-conformists who loathed Anglicans' entitlements. The advocates of “Christian history” rightly point out that conventional scholars sometimes underestimate the role of low-church Protestant zeal as a source of revolutionary fervour. Non-conformists resented the fact that, as Holly Brewer of the University of Maryland has noted, the monarch in some ways had more sway over American Anglicans than he did over the Church of England. This Anglican (and crown) privilege so infuriated dissenting Christians that it spurred them to form countervailing networks across state boundaries. But neither Presbyterian nativism, or any other sectarian impulse, would have sufficed to underpin a revolution.

As things turned out, the founding fathers—and above all Jefferson—had a much broader vision of the danger that religious intolerance of all kinds posed to the new republic. To see how sectarianism was trumped, it is worth looking at the state where freedom of conscience was first established, after a fight—Virginia.

That battle's heroes, including four of the first five presidents of the United States, were Virginian gentlemen. Jefferson saw the establishment of religious freedom in his native Virginia—overthrowing an Anglican establishment in which he, as a vestryman, had played a part—as one of his greatest feats. On his instructions, his tombstone records three things: his authorship of the Declaration of Independence, his creation of the University of Virginia (pointedly built around a library, not a church), and religious liberty in his home state.

The dismantling of Virginia's Anglican regime began in 1776, with a sonorous declaration that “the duty which we owe to our Creator, and the manner of discharging it, can be directed only by reason and conviction, not by force or violence”. This ensured there would be no repeat of the incident two years earlier when a Baptist minister was whipped and jailed for preaching without a licence. The state church was finally dislodged in 1786, when a Bill for Establishing Religious Freedom, penned by Jefferson, was passed after a lively debate in which Madison, who had been appalled by the jailing of Baptist ministers in his neighbourhood, prevailed. Madison went on to frame the Bill of Rights for the republic, including its vital provisions on liberty of conscience.