BBC News Online looks at Britain's ancient blasphemy law and how it works in practice.
The blasphemy law only protects the Church of England
Q: What is the blasphemy law?
The legal notion goes back centuries - as faith was seen as being the heart of society, to challenge or offend it was thought to threaten the fabric of society.
The present law of blasphemy is based on decisions made by nineteenth century courts. In an 1838 case it was restricted to protect the "tenets and beliefs of the Church of England".
Q: What actually constitutes blasphemous libel?
This is a more obscure. Some academics say the crime has been expressed so many ways it is hard to say exactly what behaviour would be considered blasphemous.
During a private prosecution in 1977, the trial judge said blasphemous libel was committed if a publication about God, Christ, the Christian religion or the Bible used words which were scurrilous, abusive or offensive, which vilified Christianity and might lead to a breach of the peace.
Q: How often is it used?
The last man to be sent to prison for blasphemy was John William Gott. In 1922 he was sentenced to nine months' hard labour for comparing Jesus with a circus clown. In Scotland, there has not been a public prosecution since 1843.
In 1977 moral campaigner Mary Whitehouse brought a private prosecution against the Gay News for publishing a poem, The Love That Dares To Speak Its Name, depicting a centurion's love for Christ.
Some British Muslims unsuccessfully called for author Salman Rushdie to be tried under the law after the publication of his controversial novel, The Satanic Verses. But the law only recognises blasphemy against the Church of England.
So it doesn't cover all Christian denominations?
That appears to be the case. This raises some interesting hypothetical questions. If someone allegedly blasphemed Christianity in its Church of England form, that would be a prima facie case for prosecution. But if someone insulted the faith in its other forms, such as Catholicism, it probably would not count. Trevor Phillips, chairman of the Commission for Racial Equality, says this is an example of the law's absurdity - he is a Methodist but the there is no protection for his faith under the law.
Q: Who wants to scrap it?
Many campaigners from across the political spectrum criticise the law as completely out of date and want it done away with. They argue that it is not the state's place to defend ideas and faiths - religions should be strong enough to defend themselves.
As far back as 1949, in a speech on freedom under the law, Lord Denning said: "The offence of blasphemy is now a dead letter".
Some, such as the British Humanist Association, say a blasphemy law is a threat to free speech. Others, such as Trevor Phillips, say it is unacceptable in a multi-faith society.
This ties in with thinking from a House of Lords select committee which predicted that any future blasphemy prosecution would fail because it would clash with the right to free speech in the European Convention on Human Rights, part of British law.
In 2001 Home Secretary David Blunkett said a moment would come when it would be time to confine blasphemy to history.
The Home Office had been expected to announce the repeal of the law as part of plans to outlaw religious hatred - the idea being that you protect the believer from injury, rather than the idea itself. But to the surprise of many, ministers have stopped short and blasphemy will remain on the Statute Book.
Q: Who wants to keep it?
When Labour MP Frank Dobson suggested scrapping the law three years ago, the Bishop of Oxford said the Church of England had always backed finding a workable alternative, adding: "But you have to ask, is there nothing left that is sacred?"
And attempts by Liberal Democrat peer Lord Avebury in his Religious Offences Bill to abolish the common law offence of blasphemy met with an angry response from the organisation Christian Voice.
It said: "If the committee decides not to keep the law against blasphemy it will be saying, "We do not want the United Kingdom to enjoy the blessing of God, if such exists. We are not God-fearing folk. We care nothing for God or his blessing."
Some campaigners from minority faiths would like to see the law extended to cover their own religions - many Muslims take great offence at insults against the prophet Mohammed - but there is by no means a consensus on this point of view.
But won't proposals on incitement to religious hatred protect minority faiths anyhow?
The government says no. They say the proposed law aims to close a subtle loophole: If you were to incite hatred against someone because of the colour of their skin that would be a serious crime. But if you were to do so because of their religious beliefs - that would not. The new law will protect people caught in this loophole - but insist it will not curtail frank discussion about the merits of religion.