Why should I be jailed for attacking religion?

Protection could be applied to Satanists, as well as Muslims, Christians and Hindus

Seven years in prison for a joke? Of course not, say officials at the Home Office, who are trying to present Schedule 10 of the Serious Organised Crime and Police Bill - which received its second reading in the House of Commons yesterday - as a benevolent piece of legislation aimed only at extremists. It will outlaw incitement to religious hatred without interfering with freedom of speech, its supporters claim; if this section of the Bill becomes law, it will simply protect faith groups such as Muslims, giving them the protection already enjoyed by ethnic groups.

Well, the Home Office is in for quite a fight. Two evenings ago, at the launch in the House of Commons of a campaign to oppose the new law, I found myself sharing a platform with MPs from all main three political parties, including the shadow Attorney General, Dominic Grieve, as well as the actor Rowan Atkinson and representatives of two Christian organisations, the Lawyers Christian Fellowship and the Barnabas Fund. When I spoke about defending the values of the Enlightenment to a full audience of MPs and peers, I could see the shadow Home Secretary David Davis, in the front row, nodding enthusiastically.

Why are so many people from diverse backgrounds - for once I find myself on the same side as the right-wing columnist Melanie Phillips and Don Horrocks of the Evangelical Alliance - opposed to this apparently well-meaning legislation? So far, discussion of its likely effects has focused on comedy sketches, but its implications are alarming for columnists, novelists and public intellectuals. According to the notes accompanying the Bill, it seeks to extend to religion the Public Order Act 1986, which outlaws material "intended or likely to stir up racial hatred".

The Act is drawn extremely broadly. An offender isn't even required to show "an intent to provoke a breach of the peace" or the likelihood of such a breach (let alone that public disorder resulted), nor that the defendant should intend to "stir up racial hatred by his conduct".

To secure a conviction for the new offence, it appears that it would thus not be necessary to demonstrate either that religious hatred actually had been stirred up or even that that was the intent, as long as the words were "threatening, abusive or insulting". Neither hatred nor religion is defined, so protection could be held to apply to Scientologists and Satanists as well as Muslims, Christians and Hindus.

On Monday evening, an eminent QC reported that the new offence would carry a maximum penalty of seven years. "That's you and me in Holloway, then", the Labour MP Alice Mahon whispered in my ear. Unlikely, you may say, but I have written several books and countless columns which devout believers would find offensive. A couple of years ago, I suggested that the cry of "Islamophobia" was often a way of closing down legitimate debate; I also argued that, from the point of view of an atheist and a feminist, Islam and the other monotheistic religions provide plenty of material to be phobic about.

And that is precisely why this piece of legislation is so flawed: it rests on the false proposition that it is wrong to dislike religion, when many as pects of religious teaching are incompatible with a modern interpretation of human rights.

Race and religion are not analogous, as David Blunkett seems to think. Race is a biological fact, and it is wrong to hate people because they belong to a particular ethnic group; religion is a set of ideas, voluntarily adopted, which may or may not be offensive to members of other faiths. Indeed some faith groups oppose the new law, aware that the most virulent attacks on religion come not from atheists but from members of rival faiths.

"There is a real danger", confirms Paul Cook of the Barnabas Fund, "that this law could be used by extremists to silence organisations like ourselves from highlighting the persecution of Christians." Massoud Shadjareh, chair of the Islamic Human Rights Commission, fears the legislation could be used against Muslim communities, rather than protecting them.

People need protection, but ideas do not. There are already laws that deal with incitement to violence and there is a suspicion, even among Labour MPs, that the Home Office is pushing this crass, unnecessary piece of legislation to placate Muslims who oppose the Iraq war. A number of Labour MPs are vulnerable to anti-war sentiment and even if the new law fails, as did a similar piece of legislation introduced by Blunkett in 2001, the Government will have been seen to acknowledge the concerns of Muslim voters. For such short-term electoral gain, ministers are apparently willing to ditch one of the freedoms for which this country is most admired.

For the last couple of years, I have been a member of the Foreign Office Free Expression Panel, which advises ministers and officials on threats to writers and intellectuals around the world. Right now, my advice is that they should protect Britain's reputation as a champion of free speech by telling their colleagues at the Home Office to back off.