My instincts are, I hope, as savage as the next columnist's. If an opportunity should arise for me to murder an Archbishop of Canterbury in print, then I wouldn't like to be left behind in the rush for quills and keyboards as fellow press-knights get ready for the slaughter. And there is something about the fluffy white beard and the too-long hair of this particular prelate that demands - and has now received - a bashing.

By now Dr Williams will have run out of cheeks to turn. Being described as “muddled and unhelpful” by the top Equality man, Trevor Phillips, was the least of it. The BBC Ten O'Clock News illustrated coverage of last week's speech to lawyers with pictures of handless beggars and men being flogged in public squares, as though the Archbishop had been advocating amputations and chastisement.

The Sun recommended that we all “Bash the Bishop”, probably not forgetting that this is slang for what was, for a long time, considered to be the sin of Onan. The conservative Jewish commentator Melanie Phillips exercised some extra-jurisdictional powers of her own in calling for the Archbishop to be dethroned (next week the Vicar of Dibley gives her choice of Chief Rabbi), entirely missing Dr Williams's conservative attack on the decline of civility and “customary ethical restraints” produced by our “narrowly rights-based culture”. He has even been accused of treason.

Perhaps it's the fact that the Archbishop genuinely is holier than us that has contributed to the exuberant pleasure it has given so many people to misrepresent so violently what the poor man was saying. Or what I think he was saying, for I was pedantic enough - unlike some of his most enthusiastic assassins - to read the bloody speech.

Here is my summary so you don't have to: there are lots of religious people in Britain who look to religious precepts in their solving of domestic and contractual problems, and in directing their behaviour. This is “unavoidable”. Some of these solutions are recognised in English and Scottish law, and some of them aren't. Where they aren't, we run the danger that people will both feel and be marginalised.

Not only that, but with a non-hierarchical religion, such as Islam, we risk this marginalised legal process being controlled at a local level by “primitivists” and not by wise authorities: a bit like, say, the bishops of the Church of England. If we handle this right, we could have sensible Sharia courts with legal standing, and if we handle it wrong we could have a lot of bongo-brains exercising real power, but outside the law. And we won't like that.

That's his argument. And the Archbishop was quite aware of some of the objections. Supplementary courts could not, he argued, be used to undermine human rights.

So we would have a Britain-friendly supplementary Sharia and a “market element” in law for those who freely chose it - and who, sensibly, could object to that? Neither Dr Williams nor his argument deserved the beating-up they received. And if his contribution was “unhelpful”, it was largely rendered so by the reaction to it. Obscurity rarely in itself incites hatred. But he was obscure, because it is only with great difficulty and by seeking for evidence that we can work out where his direction of travel might take us.

Once again he mentions the issue of the Catholic adoption agencies who, under the provisions of the Equality Act regulations of 2007, were forced to abandon their effective discrimination against would-be gay adoptors. This time last year Dr Williams wrote in support of the Catholic Church, arguing that “rights of conscience cannot be made subject to legislation, however well-meaning”. And again he mentions those doctors who are permitted to exercise their consciences in the matter of performing abortions. “It is difficult to see,” said the Archbishop, “quite why the principle cannot be extended in other areas.”

Well, no it isn't, actually. These “rights of conscience” have unmentioned corollaries: the gay couple denied a chance of adoption and the woman who - if surrounded by Catholic doctors - may not get the treatment to which she is entitled. It is only if such exemptions are rare that they can be at all tolerable. The implication of the Archbishop's speech is that he wants them to be less rare.

The second main problem is that members of the community who may wish or need to remain in communion can be effectively coerced into accepting inferior supplementary justice. But he never tells you how such an outcome can be prevented. How would the spread of Sharia not be accompanied by pressure on Muslims to conform to its rulings? As for the rest of us, already we are affected in myriad small ways by the supplementary decisions of religious authorities. Children can gain or be denied places at state schools as a consequence of almost arbitrary rulings on their religious status by church and rabbinical authorities. But so far we've gone along with it.

The final problem is that the Archbishop's whole approach, if adopted, would change this, not least because the new religious minorities are so much bigger than the old ones. Acting as the effective general secretary of the National Union of Priests, Rabbis, Imams and Allied Pontiffs (or PRIAPus), he privileges religion over all other kinds of identities, but fails to point out why his proffered leeway should not also be taken up by Scientologists, Mormons, football clubs, political parties and any other community that offers “social identity and personal motivation”. Why should certain doctors not refuse to see women patients? Or deny blood transfusions? Why should Spurs- supporting cab drivers not dump Arsenal passengers in South London?

He meant well. In T.S.Eliot's play Murder in the Cathedral, before Dr Williams's predecessor Thomas à Becket gets hacked to death, he is visited by various temptations. “The last temptation is the greatest treason: To do the right deed for the wrong reason.” Eliot was mistaken; even worse is to do the wrong deed for the right reason.

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