Leading article: The Archbishop has stepped into a political and intellectual minefield

The Archbishop of Canterbury's speech this week on the relationship between civil and religious law is a hopeless intellectual muddle. Dr Rowan Williams argues that the UK must "face up to the fact" that some citizens do not relate to the British legal system and that "the law needs to takes some account of that". One of his suggestions is "a constructive accommodation with some aspects of Muslim law".

The glaring problem with such an "accommodation" is that only Muslims would be bound by sharia. In a liberal and open society all citizens must be equal before the laws of the nation. There can be no laws which apply only to certain religious or cultural groups. Dr Williams says the idea that there is "one law for everybody and that's all there is" is dangerous. On the contrary, that unified legal system is what underpins our freedoms. If Dr Williams thinks "one law" is dangerous, he should consider the social consequences of different groups being governed by different legal jurisdictions.

Dr Williams's desire to make life easier for Muslims and other minority faiths "faced with the stark alternatives of cultural loyalty or state loyalty" is laudable. But the archbishop fails to make a distinction between specific laws to protect vulnerable minorities – such as the incitement to racial hatred – and the idea that certain religious groups should be allowed to establish the laws under which they live.

This does not mean any cultural and religious traditions should be trampled into the dust. Under the existing law, individuals may devise their own way to settle a civil dispute in front of an agreed third party if both sides agree to the process. This is the reason Orthodox Jewish courts exist. There are even some areas of Britain served by sharia courts. There is nothing wrong with the existence of these councils in principle. Indeed, it is often a cheaper and quicker way for their participants to settle a dispute than going through the real courts.

But Dr Williams seems to want to take it a stage further and make them into a sort of parallel legal system. This is intolerable. If anything, the Government should be demanding greater oversight of these religious courts to ensure that the participants (particularly women) are not bullied into accepting its verdicts and know that they have recourse to the genuine law of the land.

This intervention is intellectually misguided. But it is also foolish on a political level. By suggesting that sharia is "unavoidable" Dr Williams unconsciously echoes the rhetoric of the reactionary right, which likes to present Islam as an advancing threat to the British way of life.

The Archbishop is right to argue that popular perceptions of what sharia means are somewhat skewed. Mention the word and many people in this country will think of extreme punishments, the murder of apostates and the oppression of women. Dr Williams is justified in pointing out that to regard the sort of sharia practised by the Saudi Arabian state and the Taliban as the only true interpretation of Islamic legal teaching is a calumny on all tolerant Muslims. But, all the same, Dr Williams should have known that his intervention would be interpreted as condoning such brutal systems. He also took no account in his speech of the many hundreds of thousands of Muslims in Britain who do not want to see an extension of the influence of sharia law in their lives.

Dr Williams claims that he merely wishes to increase social cohesion and promote tolerance in Britain. But all he has succeeded in doing is fanning the flames of hostility to Muslims. This intervention was a naive blunder and one which we trust the Archbishop will not repeat in a hurry.