The Big Question: What is equality legislation, and why is the Pope so concerned about it?

Why are we asking this now?

The Pope has made an extraordinary intervention into British politics by urging Catholics to oppose the Equality Bill going through Parliament. The Bill has finished its passage through the House of Commons, and was being fiercely debated in the House of Lords last week, with religious groups lined up on both sides of the argument, and may become the cause of a stand-off between MPs and peers.

The Pope told a gathering of English and Welsh Catholic bishops, in Rome, that the legislation would "impose unjust limitations on the freedom of religious communities to act in accordance with their beliefs," and added: "In some respects it actually violates the natural law upon which the equality of all human beings is grounded and by which it is guaranteed." The impact of his words is all the greater because he will be soon be making the first papal visit to the UK since 1982.

What is the Equality Bill?

Of all the legislation going through Parliament, the Equality Bill, as sold in government bookshops, is the fattest. It fills 600 pages. At £13, it also the most expensive, except for certain highly technical bills that have only a narrow application. Part of the reason it is so long is that alongside the legal text there is a running commentary. Equality legislation is well known to be a minefield of misunderstandings, and Harriet Harman, the minister behind the Bill, is hoping to limit the number that this one causes. But it is also long because it covers a lot of ground.

What is the Bill supposed to achieve?

Despite its daunting length, one intention behind the legislation is to simplify the law. It supersedes a lot of old laws, rolling them all into one, so that employers only have to refer to one text to make sure they are complying with anti-discrimination legislation. Despite the controversy, Ms Harman believes the Bill will be law before the General Election. Most of it will come into effect this autumn, though some parts will not apply until spring 2011.

Whom does it protect?

The Bill introduces a new phrase into the English language, which will sound strange to many people's ears. Where somebody used to be part of an oppressed minority, they now have what is called a "protected characteristic". If you think that phrase does not apply to you, you are wrong. Everybody has some "protected characteristics", but some people have more than others. They are the ones most likely to suffer discrimination.

What are these 'protected characteristics'?

There are nine categories listed in the Bill: age, disability, "gender reassignment", marriage and civil partnership, pregnancy and maternity, race, religion or belief (including lack of belief), sex, and sexual orientation. The last two are universal, because, with very rare exceptions, we are all either male or female, and we each have a sexual orientation. The law is meant to protect men as well as women, and heterosexuals as well as gay people, where necessary. The smallest category on the list is "gender reassignment, which applies to people who are planning or undergoing or have been through a sex change.

Do we really need one law to protect all these different types?

In the old days, there was a law against racial discrimination, another against sex discrimination, and so on. There were also different agencies to battle for teach for each of the groups targeted. So when people who opposed "political correctness" made jokes about the mythical "one-legged black lesbian" being overprotected by law, they missed the point. A person who was being picked on because they stood out in several different ways had to choose whether to seek protection against racism, or homophobia, or prejudice against the disabled, but not choose two at once, because there was no single law banning discrimination with multiple "protected characteristics". The Equality Bill will allow someone to claim discrimination relating to two – but not three, or more. Even Harriet Harman thinks two is enough to cover almost all likely cases.

So what is the Pope's objection?

The Equality Bill was designed to have an impact on religious organisations which employ people in secular jobs – secretaries, administrators, youth workers etc – by making them subject to the same anti-discrimination laws that apply to other employers. The churches are not opposing the Equality Bill as a whole, but some – though not all – are forcefully arguing that they should be exempt from this section of the Bill. Their religion teaches that gay sex is sinful, and they argue that it would be an attack on their religious beliefs if they were compelled to work with people known to practise it. Now they have the Pope on their side.

So this comes down to an argument about gay priests?

Anti-discrimination laws have never fully applied to religious groups. Otherwise there could have been any number of clashes with the law, not just over gay people, but over the issue of whether women should be allowed to preach. The Government says that even under the revised law, the appointment of clergy and religious teachers will be exempt, as always, but their opponents are not convinced.

What are those opponents saying?

The Tory peer Detta O'Cathain, who led the opposition in the House of Lords, argued: "A belief in freedom of association demands that, even if we do not share the beliefs of an organisation, we must stand up for its liberty to choose its own leaders and representatives. I accept that the Government intend to protect the freedom of churches to choose their own staff, but their wording does not mirror that intention."

Her argument is that a religion that prohibits gay sex should not have to employ someone openly gay any more than a Rape Crisis Centre should be made to employ a male counsellor.

And supporters of the Bill?

On the other side were people who thought that the Equality Bill does not go far enough, including the Labour peer Waheed Alli, who is gay and a Muslim. He said that any priest in any religion who is sacked for being gay should have the right to sue for unfair dismissal. He also believes that the law should recognise civil partnerships where the ceremony is conducted on religious premises or involves a religious element, which is not allowed under current law.

And what does Harriet Harman say?

"We have never insisted on non-discrimination legislation applying to religious jobs such as being a vicar, a bishop, an imam or a rabbi," she said yesterday. "Religious organisations can decide themselves how to do that. However, when it comes to non-religious jobs, those organisations must comply with the law."

Is there any case for the Pope intervening in British politics?

Yes...

* The Equality Bill will apply to churches, and therefore church leaders have a right to express opinions

* Churches have the right to choose to employ people who share their doctrines

* The Pope is not asking for special treatment for Catholics. He just wants the law to stay as it is

No...

* Churches are also secular employers and should obey employment law

* The Equality Bill is not going to apply to bishops, rabbis, imams or other religious leaders

* Believers cannot claim that their freedom of worship is threatened if someone who is gay cleans their church or does the accounts