In Mitt Romney’s carefully choreographed, partly self-financed and meticulously planned campaign for president, last week’s speech was premature. He always intended to give a speech at some point, addressing the fact of a Mormon running for president. But he assumed he’d give that speech after his nomination by the Republicans, pitching a general and uplifting message to all Americans about the need for religious liberty and pluralism.

The only reason he gave the speech last week is that he felt he had no choice. In Iowa, a critical state for his momentum-based candidacy, he was slipping into second place. The insurgent, Baptist minister Mike Huckabee, was subtly appealing to the overwhelmingly fundamentalist Christian voters of the Republican base. Hucka-bee ran a disgraceful ad touting himself as a “Christian leader”, “defined” by his faith. And the pool of votes Romney had been banking on began to shift rapidly away from him.

And so the speech itself, entitled Faith in America, had to be a little different. It was not in the end a call to American pluralism. It was a rallying cry to all believers to wrestle the public culture of the United States away from nonbelievers. It was a pitch designed to say that whatever doctrinal differences Mormons have with mainstream Christians, they are trivial compared with the war against secularism.

So we were told, rather baldly: “Freedom requires religion just as religion requires freedom . . . Freedom and religion endure together or perish alone.” Of course freedom and religion can go together. But freedom requires religion? There are many free, secular societies where this doesn’t seem an exhaustive explanation. And while freedom of conscience can indeed be defended by religious doctrine – just read your John Locke or Second Vatican Council – it has also in history been persecuted and repressed by religion. Why were Locke and the second council even necessary?

And then you noticed that Romney’s embrace of pluralism does not actually include atheists or agnostics or those with no faith at all. This was not a minor oversight. In fact those who want to preserve a secular hue to public debates were given no quarter: “It is as if they are intent on establishing a new religion in America – the religion of secularism. They are wrong.”

Romney, moreover, explicitly stated a core religious doctrine of his: “There is one fundamental question about which I often am asked. What do I believe about Jesus Christ? I believe that Jesus Christ is the son of God and the saviour of mankind.” If his point were to say that it is irrelevant what your religion is when you run for president, merely that you have a religion, then why this explicit statement? It tells his audience that he is not a Jew or a Muslim.

In his famous 1960 speech to the Houston ministers, John F Kennedy issued no such theological credo. And the explanation for Romney’s doing so is pretty simple: he wants the political benefit of being a Christian without the political cost of being a Mormon “Christian”. The speech was therefore a purely political manoeuvre, as is almost everything that comes out of Romney’s mouth. In order for a Mormon to win over the Christian right, he has to unite with them against a common foe: the religion of secularism.

To do that, he needs to have a broad public embrace of Christ, but not of the actual doctrines of his own church. Recall that Romney is not just a Mormon but has served as a bishop, and for nine years was a stake president – a position of considerable authority and power within his denomination. He knows the doctrines as well as anyone, but he will only explain that part of them that reassures the Christian right.

Will they be reassured? That remains to be seen. By touting active faith as the prerequisite for American public life, Romney appeals to those who see religion primarily as a benign force in American culture. He effectively says to the Christianist right: I’m with you on abortion (even though he long wasn’t), on gay rights (even though he once claimed he’d be more pro-gay in the Senate than Ted Kennedy) and in favour of appointing justices who would get out of the way of Christian majoritarianism. So forget about our theological differences. What matters is that someone believes in something and advances your political agenda.

Romney, it should be remembered, is not the first Mormon to run for president. That distinction is awarded to the founder of Mormonism himself, Joseph Smith Jr, who ran in 1844 on an abolitionist platform and in defence of the rights of religious minorities. Mormon political history has long been strongly secularist in this respect – because Mormons were once a sect brutally persecuted by majority Christians.

But in that campaign, Smith coined a term that strangely resonates today. “There is not a nation or a dynasty now occupying the earth which acknowledges almighty God as their lawgiver,” Smith told the Neighbor newspaper in Nauvoo, Illinois. “I go emphatically, virtuously and humanely, for a theodemocracy, where God and the people hold the power to conduct the affairs of men in righteousness.”

Theodemocracy: the blending of government with a universally Christian populace in which faith is the prerequisite of public office. This is the vision of America that Romney is proposing. He has behind him the power brokers of the Protestant right, the theocons of the Catholic right, the Mormon church and the vested interests of a Republican party elite that, in the wake of George W Bush, wants to extend the theodemocratic principles of an antisecular movement.

Romney has in front of him all those – believers and nonbelievers – who feel that too overt a religious identity in the public square is a dangerous tyranny of the majority, and the true believers whose faith is not instrumental to anything but itself.

And that’s why, in my view, what Romney represents is not quite as benign as he makes it out to be. I would have had no qualms in supporting a Mormon for the presidency, as long as he vows to represent people of all faiths and none. But Romney decided against that. That matters. It is veiling intolerance under the guise of tolerance.

Nonbelief is rooted in the same freedom of conscience as belief. In fact they are inseparable. Freedom of religion must mean the right to come to the conclusion that there is no God at all. By eliding that critical piece of American mosaic, Romney revealed that he isn’t actually a pluralist. He is the anointed son of the organised religious right. And his own religion is still irritatingly in the way.

Times Recommends

• It’s not just about Iraq, it’s about Blair’s style
• You can’t rank hospitals like football teams
• Minarets are not an essential part of Islam