One of the big problems in this field is that there's so much mystification that surrounds talk of the Shari'a, whether its saying that Islam is all about peace or whether its people saying that Islam is all about Jihad and all about suicide bombs. People will make statements which don't seem to be backed up by any sort of historical context.

In 1979, you had the revolution in Iran. You had the Hudood Ordinances in Pakistan, which are the laws that are notoriously used against women, which are theoretically used against thieves although they're never carried out - an actual amputation or an actual stoning. The blasphemy laws, again, never actually carried out, though they're there, heavy with menace on the statute books.

My father's from Pakistan and he has been a secularist all his life. In the Pakistani context, there's no messing with religion. There's been a battle for the soul of Pakistan since 1947 and I have grown up without any illusions about the dangers of religious power in the context of a country like Pakistan.

There were periods in Islamic history when things like apostasy and blasphemy were made punishable. So you know it kind of depends - there's no argument, quite apart from the question of the divine or otherwise nature of the Qur'an, that huge swathes of Islamic law are man-made. Clerics here - in maintaining their power, will often try to elide that and say "Well no, actually this isn't man-made at all. Stoning is part of the divine revelation." It isn't in the Qur'an but the way this has been done over the years is to take the Hadith.

Ayatollah Khomeini issued a fatwa to that effect, which was then given effect in the Islamic Republic of Iran, so in the Islamic Republic of Iran, it's flexible enough to allow for sex changes, and it encourages sex changes. But if you want to change your religion in Iran, you've got some serious problems. There are other problems. You're allowed to change sex, but if you want to be a homosexual, theoretically at least, you face the death penalty. Quite how often these penalties are carried out is a moot point, but it's there on the statute books.

I work in the human rights field and there are serious conflicts between certain interpretations of Islamic law and human rights. That's something which I don't make any bones about at all, it's something which I think is very important for everyone to address, including the Muslim community, and many Muslims are addressing that issue.

I spoke to my father - my father's from Pakistan and he's also a lawyer - I said to him, "Well what does the Shari'a say?" And he said, "Well, of course it doesn't justify suicide bombs," but he didn't seem to know where the Shari'a came from or what it was all about. The more I asked people in my family as well as friends, the more I realized that there seemed to be widespread ignorance in the Muslim community. And that's something which I actually found to be the case over the next two and a half, three years I spent writing the book.