Antidisestablishmentarianism is on the march. Which is odd, considering there is only the faintest whiff of disestablishmentarianism to fight. The Archbishop of Canterbury set this hare running with his usual confused mumbling into his beard. To disestablish the church would be "by no means the end of the world", he said bravely. He hastened to add that he did not want the church sundered from the state right now. And he would oppose "secularists [boo, hiss] trying to push religion into the private sphere". This sent the Telegraph and Mail into a spin, claiming a devilish distestablishment plot on the Labour backbenches - though they could find only three usual suspects. These MPs say the likely move to end the 1701 Act of Settlement that bars Catholics from the throne will make an established church impossible.

How likely is this? Look at how Tony Blair and Gordon Brown have promoted faith and religiosity as "community", and ask yourself if there is the faintest chance that Labour spends untold parliamentary time unpicking the cat's cradle of a relationship between church, Lords and crown? Frankly, if Labour had the inclination for constitutional reform, first priority should be ending our disastrous first-past-the-post voting system.

True, it is embarrassing to be the only western democracy that has theocracy built into its legislature. The 26 bishops in the Lords interfere regularly: they are a threat on abortion, and their campaign sank the Joffe bill, giving the terminally ill the right to die in dignity. Of course they should not be there, when only 16% of people will grace the pews on Christmas Day, and Christian Research forecasts church attendance falling by 90%. But a dying faith clings hard to its inexplicable influence on public life.

Labour has encouraged the power of the religions to a remarkable degree, consulting them on endless committees. To be an atheist is now unacceptable in a political leader: when Nick Clegg confessed his non-belief, he had to recant and re-define himself as an "agnostic". The BBC is increasing religious broadcasting; Radio 4 already does 200 hours. Is this by popular demand? No. An Ofcom survey put religion last in the public's interests. Expect a worsening clash in the new Equality Commission between religious rights and gay and women's rights. The Islington registrar who refused to conduct civil partnerships for religious reasons was an ominous landmark case.

This has been the year of religion's fightback against secularism - a word made almost synonymous with the spiritual and moral decadence of materialism. Angered by the runaway success of anti-God books by Richard Dawkins, Christopher Hitchens, AC Grayling and others, the different faiths - though each believes it has the one and only divinely revealed truth and often fights to the death to prove it - combine in curious harmony against secularists.

They blame us for all the evils of modernity, as if they could point to some morally better time when people feared God and sinned less. There is, of course, no evidence that God-fearers ever behaved better than the ungodly. One of the great mysteries of religion is why, even when people believed that heaven awaited the virtuous and everlasting torment was the destiny of sinners, there is no sign it made them any less prone to all the sins flesh is heir to. Yet they turn on atheists for lacking any moral base without a God.

I could say we are mortally offended and demand protection from such insult. But it is the prerogative of religions to be protected from feeling offended. Priests, imams and rabbis reserve for their beliefs a special respect, ringfenced from normal public argument. It is abusive and insulting to suggest that belief in gods and miracles is delusional, or that religions are inherently anti-women and anti-gay. Meanwhile, non-believers suffer the far worse insult that we inhabit a moral vacuum. But we will live with the insult if we are free to reply that there is no inherent virtue in being religious either: it does not make people behave better.

The unctuous claim there is a special religious ethos that can be poured like a sauce over schools and public services to improve them morally has been bought, to a depressing extent, by Labour, and over a third of all state schools are now religious institutions - despite overwhelming evidence that their only unique quality is selection of better pupils, storing up trouble with ever more cultural segregation.

Here is an enjoyably impudent piece of research from Innsbruck University. People were observed buying newspapers, using an honesty box to pay. They were interviewed later - so the person with the clipboard seemed unconnected with the newspaper purchase - and asked about age, occupation and attitudes. Men cheated more than women; people over 50 cheated more than the young; higher education made no difference; and by a long chalk churchgoers cheated most. This may be a statistical anomaly. But we all know one thing: religion no more makes people good than lack of it makes the rest of us bad.

Secularists take offence too at the way the religious paint unbelievers as poor desiccated rationalists, not only without values, but joyless, lacking a sense of mystery, devoid of awe. Yet, earthbound, there is enough wonder in the infinite capacity of the human imagination, in a magical world of thought, dream, hope, memory and fantasy. To be human is not to be particularly rational, the senses often overwhelming common sense. There is no emotional or spiritual deficiency in rejecting religions that infantilise the imagination with impossible beliefs.

In January many more atheist buses - an advertising campaign launched on Comment is Free - will roll on to the street than expected. The British Humanist Association is astonished at the response - a target of £5,500 has swelled to £130,000, most in small donations. The buses will bear as good a message as any this Christmas: "There's probably no God. Now stop worrying and enjoy your life".

• Polly Toynbee is president of the British Humanist Association and honorary associate of the National Secular Society

polly.toynbee@theguardian.com