The rule of polite dinner party conversation — avoid mention of religion and politics — has been turned on its head in recent weeks as the churches and mosques got involved in politics associated with the recent local and European elections. Some church leaders used media appearances to denounce the BNP's policies on immigration and asylum as un–Christian. The Catholic Church went deeper into the political arena, with church leaders claiming that a booklet, Cherishing Life, which they issued last month, was more than a statement of moral principles and viewpoints. It was, they said, a guide to their congregation on how to participate in the political process and the (then) forthcoming European and local elections.

This document argued that Britain was facing a moral crisis, a culture of death —with widespread infanticide (abortion) and general disregard for the sanctity of human life. The Bishop of Cardiff even made the claim on the radio that many elderly and sick people were being murdered in our hospitals to free up beds, in an epidemic of non–voluntary euthanasia.

What should the secular response to this intervention be? First, it is self–evident that individuals with strong views based on religious beliefs have the right to get involved in the political process. A significant minority of MPs claim that their prime motivation for entering politics was their faith, and such MPs are found in all parties. It has to be pointed out that these MPs are not a bunch of really nice people swimming in a morass of back–stabbing and deceit. In my experience, they are as nice and as nasty as the rest of us.

However, I would go further and argue that not only is it legitimate for such people to get involved in politics but that they should be encouraged to do so. It is far better that religious opinions are heard explicitly within the mainstream political arena than that these communities feel excluded from it. That would merely provide a stronger incentive to seek to exert covert influence behind the scenes outside the public democratic debate.

An increase in faith–based state schooling is about the worst policy the Government has come up with. It has never been debated in parliament as a government measure. As far as I am aware the Labour Party Conference has not endorsed the idea (although opposition by the party at large to a Downing Street policy appears to be a prerequisite for its adoption). There must have been some secret meeting and lobbying by the faith groups, especially the Church of England, before the Government published its education plans in the last White Paper.

If the religious views of the Prime Minister and his advisers are of relevance to the development of policy, this would be even more worrying, since religious alliances are by definition exclusive and to a certain extent below the political radar. Covert Masonic influences in public life are, quite rightly, frowned upon and indeed regulated. There is an equally strong case for ensuring that religious interests are fully disclosed where this is relevant to public policy or expenditure decisions, or might be seen to be.

The Catholic Church and other religious organisations have every right to publish what they call 'moral manifestos' and urge their adherents to place their vote appropriately. Again, it is explicit and can be debated freely.

Except, that is, on Radio Four's 'Thought for the Day', where religious protagonists have the unique privilege of avoiding questioning or interruption from John Humphrys and Jim Naughtie with which the rest of us have to cope!

What we have to ensure, however, when religions publish such manifestos is that they do not get away with the implication that 'moral' can be equated with 'religious'. Religion does not have a monopoly on morality.

As I argued on the Today programme recently, what one religion may consider to be moral and 'life–cherishing', other religions or freethinking people may consider 'immoral'. I used the example of the Catholic Church leadership's policy on condoms and HIV/Aids in Africa. I described this as immoral and death–causing. Many Catholics agreed with me. Indeed, when I visited Malawi last week I found an Aids clinic using Cafod (Catholic Fund for Overseas Development) money to support its HIV testing and education services (including the issuing of condoms). That Catholic charity was living and working in the real world. In contrast, the funding it received from the US National Institutes for Health — not a religious body — could not be used for life–saving contraception, thanks to the Bush administration, which has been extensively lobbied and funded by right–wing religious groups.

Politicians and society at large need to be particularly careful about religious lobbying because, almost uniquely, many religious positions are not subject to change when the evidence changes or when the circumstances change. Such positions are articles of faith or revealed scriptural truth.

There are many views with which we can disagree, but we should be particularly concerned about the imposition of policy with which we disagree when its basis is deemed immutable and resistant to rational analysis. This method of religious lobbying can be exposed in open public debate, but is dangerous when granted immunity from scrutiny: when done behind closed ministry — church or government — doors.