Does the seizure of the Labour leadership north and south of the border by Presbyterian progeny signal the revival of religion in British public life? Both Gordon Brown and Wendy Alexander are self-consciously "children of the manse": happy, we are told, to bring their Protestant sensibility to bear upon public policy. Whether it is opposing supercasinos, or rolling back cannabis liberalisation, or calling for a "coalition of conscience" against the atrocities in Darfur, the Presbyterian ethos of "giving witness in life" has returned to the higher echelons of government.
But this is eyewash: the Protestant mindset has rarely played less of a role in Labour politics than now. A movement that once owed more to Methodism than Marx has lost sight of its religious prehistory. Thanks to the fashionable, secular fundamentalism of writers such as Richard Dawkins and Christopher Hitchens and the unattractive evangelism of the US "moral majority", the British left has systematically abandoned the progressive Protestant voice. Labour's sense of mission is poorer as a result.
The Protestant inheritance has long been divisive. From the outset, the Reformation contained within it radical and conservative readings. While Martin Luther's split from Rome in 1517 offered a template of rebellion, his stress on scriptural authority (sola scriptura) gave the Bible's conservative edicts new force. Particularly attractive to authoritarian Protestant princes was Romans 13:1 - "Let every person be subject to the governing authorities. For there is no authority except from God, and those that exist have been instituted by God." Here was godly sanction for state autarchy - a Protestant tradition of conservatism that would eventually find a British voice in "Church and King" Toryism.
But a reading of the Book of Acts could lead believers in a different direction: "We must obey God rather than man." For those Anabaptists in 1530s Münster and Calvinists in 1550s Edinburgh who decreed that their governments were in opposition to the rule of God, the response was revolution. Indeed, much of modern resistance theory - the duty to overthrow despotic authority that inspired revolutionaries in 1640s England and 1770s America - stems directly from the Protestant tradition.
Along with this came a focus on equality. In place of the inequitable hierarchy of the Catholic Church, Luther posited a "priesthood of all believers". But, his poorer followers were not slow to ask, why not social justice together with spiritual equality? In the beautiful words of William Tyndale, the genius translator behind the King James Bible, "As good is the prayer of a cobbler as of a cardinal, and of a butcher as of a bishop; and the blessing of a baker that knoweth the truth is as good as the blessing of our most holy father the pope." This was the socialist imperative of Protestantism, which would inspire generations of radicals, from the peasant leader Thomas Müntzer in 1520s Germany to the Methodist revival of 18th-century England to the civil rights mission of Martin Luther King, Jr.
With the scriptural reasoning came a culture of resistance and triumph. The Christian narrative of redemption, chronicled majestically in Bunyan's Pilgrim's Progress, was transposed into the political realm. Socialism, a religion of humanity, was susceptible to this spiritual paradigm. So the most successful recruiting sergeant in the British socialist canon, Robert Tressell's Ragged Trousered Philanthropists, can only be understood fully as part of the Protestant tradition. In his charity and ascetic holiness, Frank Owen is a missionary operating in the darkest heathen terrains. His lonely, arduous work converting the fallen philanthropists - the hapless painters and decorators of Mugsborough - to Marxian socialism is a chronicle of sacrifice worthy of any biblical parable.
This tradition, of equality, duty and intense literacy, was Labour's religious preamble. For, uncomfortable as this may be to today's secular enthusiasts, the Labour movement from its earliest days was joined at the hip to Protestant Nonconformity. Its foundation place, the Congregational Memorial Hall in Farringdon Street, London, was a monument to one of the defining moments in Puritan history - Charles II's ejection of Dissenting ministers from the Church of England in 1662.
Early membership of the Independent Labour Party found its strongest support in the Nonconformist chapels of West Riding, County Durham and South Wales. The spirit of Dissent was felt keenly by its first leader, James Keir Hardie, who regarded socialism and Christianity as philosophical bedfellows. "The impetus which drove me first of all into the Labour movement, and the inspiration which has carried me on in it, has been derived more from the teachings of Jesus of Nazareth, than from all other sources combined," he explained in 1910. "The Labour movement in its very essence is essentially religious."
Of particular inspiration for Labour's founding fathers was the Puritan example. Calvinist in theology, the "godly sort" of the early 17th century had been the motors for both the founding of the American Commonwealth and the energy of the English Civil War. Their moral rectitude and political certainty were rediscovered in the 19th century, as a statue of Oliver Cromwell was placed before parliament. In a transparently Puritan vein, Hardie began as a temperance campaigner and regarded abstinence, clean living and even vegetarianism as prerequisites for the life of a true socialist. Ramsay MacDonald was similarly infused with Roundhead spirit and in 1912 published "A Plea for Puritanism". "With the Puritan, character must always count," he lectured the troops of the nascent Labour movement. "The Puritan can no more ask what has private character to do with public life than he can ask what has theft to do with honesty."
The cult of abstinence continued into the 20th century in the fastidious form of Stafford Cripps and in the equally ardent teetotaller Tony Benn. Indeed, Benn's childhood memoir, Dare to Be a Daniel, is a celebration of the Puritan spirit: his early days were spent listening to Old Testament tales from parents who lived next to the Tate Gallery but never went inside. Benn's obsessive diary-keeping is a product of the Puritan impulse: a combination of personal vanity with an obsessive commitment to record every hour and justify it to God. But Benn himself is in denial about this Puritan genealogy. Talking to me last year among the pews of Burford Church in Oxfordshire - commemorating Levellers' Day - he insisted that the Labour Party was a secular institution born of a collective of workers, trade unionists, socialists and intellectuals. The Dissenting tradition had been politely excised.
His voice is a common one. Despite the church service that will begin this month's Labour conference, Protestantism is largely absent from the modern party's policymaking and ethos. Of course, Christian groups play a role around the edges - notably in the Jubilee 2000 and Make Poverty History campaigns - but the still, quiet voice of Puritan struggle has been lost. An ambitious young backbencher would be far wiser to join Labour Friends of Israel than the Christian Socialist Movement. Moreover, among leading figures within the party's powerful Scottish caucus, Catholicism often plays a stronger card.
This spiritual amnesia is strange, given the intense religiosity of the last Labour leader. But Tony Blair's Protestantism was of an ecumenical, Anglo-Catholic nature (witness his Cardinal Newman gift to an indecently grinning Pope) and wholly devoid of the grinding self-doubt central to the Puritan soul. There was certainly a Manichaean tinge to his geopolitics - with its arcs of extremism and its existential struggles against Islamism - but little historic connection to the "Good Old Cause".
Brown is different: raised in the precepts of the Church of Scotland, he is a Puritan in the greatest sense of the term. Despite dismissing the label at a recent press conference with a misquotation from Mark Twain ("It [London] was no place for a puritan, and I did not long remain one"), his seriousness and even dourness shine through as readily as Maggie Thatcher's Methodist make-up. Visitors to Downing Street these days find an air of closed-door, hushed studiousness in contrast to the more gregarious Blair days. Only someone with Brown's Calvinist inheritance could conjure the slogan "Make Work Pay". He also seems to be thinking more broadly about the Protestant sensibility, citing the anti-Nazi Lutheran pastor Dietrich Bonhoeffer in his recent book Courage: Eight Portraits, and looking closely at the attempt of the Democrat evangelist Jim Wallis to revive progressive Protestantism in America.
But Brown is in the minority. Today, we don't want morality from our politicians: the examples of Pat Robertson in the US or Ian Paisley in Northern Ireland make many on the left instinctively wary of faith-based politics. Yet there remains so much unique to the Protestant tradition - its calling of autonomy and equality; its culture of education and literacy; and its genealogy of struggle - that the left should cherish. To abjure this inheritance for a knee-jerk, left-liberal atheism is a product of both historic illiteracy and intellectual arrogance. Instead of denying its Protestant past, the Labour movement should lift up its eyes and reacquaint itself with the party's founding principles.
Tristram Hunt's TV series "The Protestant Revolution" begins 12 September at 9pm (BBC4)