This kind of secular approach has its origins in the European Enlightenment of the seventeenth and eighteenth centuries. After a period of savage religious wars, there was a strong and understandable desire to avoid further conflict over religion, and a deep suspicion of religious authority as oppressive and irrational. Many intellectuals believed that moral behaviour, combined with a vague reverence for a supernatural creator, was something that all reasonable people were capable of grasping and putting into practice; they did not need revelation from heaven, or religious institutions with priests and sacred books to tell them what they could work out for themselves. So religious authorities had no place in the government of a country; and many thought they had no place at all, and tried to abolish them - as in the early days of the French Revolution.

As the modern age developed, a further element came to play a part in this. The idea of human rights became increasingly powerful. For many if not most who thought about it, this meant that each human individual was born with an intrinsic claim to be treated with respect, possessed of a natural dignity and liberty which should be recognised by the law. That liberty was essentially a freedom to choose what would make him or her contented; and it was obviously limited by considerations of harm to others. A reasonable and fair society would be one in which each person's freedom to choose and to pursue their happiness was respected and each person was protected from being seriously disadvantaged by someone else exercising their freedom. This became an important aspect of modern capitalism, with its goal of increasing every individual's range of personal choices.

So the ingredients developed of a particular kind of modern secularism. On the basis of what I have been describing, the ideal society appears as one in which the government as a whole does not promote the values of any one philosophy or religion, except to affirm universal human rights to free choice; it does not give public recognition or support or privilege to any religious body, though it allows religions to exist as private associations, so long as they do not threaten the way in which society overall carries on its business. In different degrees, this is the assumption behind several modern societies: France is the clearest example, but the USA, despite its high level of religious practice, is in theory committed to this as well. Other countries - Britain, Germany, Italy, for example - have a more complicated position in which there is still a measure of public recognition for religion, though there is fierce debate about whether that is a good thing in contemporary circumstances. But this debate is more and more raising questions about the basic model of a 'secular' society and what it means. In this lecture, I want to look at some of the unanswered questions in my own context, and to ask whether these questions have anything to suggest about the relation in other contexts between religious institutions and society or law. As I do this, I shall be speaking primarily about Christianity; this is not because similar questions don't arise in relation to other faiths, but because it is my own faith and, historically, the faith of my own culture - but also because there are areas where it raises what I believe to be some highly distinctive issues that other faiths do not so clearly deal with.

I begin by noting that the Enlightenment position has as a matter of fact been seriously undermined by a range of philosophies that have questioned some of its deepest beliefs. The development of psychoanalysis has undermined the idea that everyone begins with a clean slate of reasonable mental processes which can be relied upon to deliver universal truths. Marxism insisted that the most important freedom was not individual choice in the usual sense but control over the processes of production and marketing on the part of those who actually operated the processes, and that the most important engine in human history was the struggle over this. Awareness of the diversity of cultures in the world brought an uncertainty about whether any values could be more than local and whether any claims to universal reason could make sense. In their different ways, all these made it harder to accept without question the optimism of the classical secular, rationalist model of social life. But equally they made it harder to establish any acceptable theoretical framework for society; increasingly in the Western world, and more recently in what used to be the Communist world, the result has appeared to be a model of society which still accepts human rights as a set of entitlements for individuals, but which sees society as no more than a system by which individuals are given the minimal level necessary for protection and the condition for market choice or consumer choice are safeguarded.

Two things at least have focused the attention of different sorts of commentators on the unfinished business represented by this model. The first, which is most often discussed by left-wing critics, is that the market, while it is obviously the main organ by which any society secures and develops its common prosperity, does not ensure anything like an equitable distribution of resources. Both within particular societies and between different nations, damaging inequalities have grown, to the extent that they begin to affect the proper functioning of societies themselves. The debt crisis, to which so much attention has lately been given, brought to light some of the ways in which the pressures of the global economy could work to the disadvantage of poorer nations. We are more aware than ever of the difficulties of securing real fairness in trade conditions for countries that have never had a foot on the ladder of the world economy.

The second is something more often pointed out by conservative critics of our modern situation. When our culture is so full of the language of relative values and so obsessed with consumerist patterns of behaviour, where is it that people get the motivation to act for the sake of others or simply to value things that are not of immediate economic use? Until fairly recently, the inequalities of society were made less stark by the many networks of voluntary agency and charity that looked after those who were overlooked and damaged by wider social processes. But our age is one in which the spirit of volunteering is less in evidence. What is more, if society has no moral orientation by which to guide younger citizens, what will fill the gap? As stable patterns of family life are undermined by the same short-term consumerism that prevails in economics, as people become less and less willing or psychologically able to make the long-term and unconditional commitments of marriage and parenting, we cannot assume that children will grow up with clear moral priorities. And the effect, as recent studies in the UK have shown with alarming clarity, is not a generation of free spirits, but a generation of young people who are often bored and unhappy in a new and worrying way, vulnerable to mental illness as never before.

The rational philosophy of educated Europe over the last couple of centuries has been weakened. One of the paradoxes is, as the present Pope has rightly pointed out, that many people now mistrust and undervalue science almost as much as they do religion, because they do not take for granted the same confident attitude to reason and objective argument. And because scientific and technological advance has brought its own nightmares and crises - nuclear warfare, genetic engineering, environmental pollution - it is not surprising that many feel this mistrust. The philosophy of human rights remains the cornerstone of so much of what we do in our legal systems; but we are more aware of the clash of competing rights, the risks of individualism, the assumption that I can always enforce what I believe is due to me. We are beginning to see that these things create a society that is aggressive and suspicious, where trust is in short supply.

So a society that never asks questions about the Enlightenment model is one that is going to be in many ways an unhappy, anxious, fragmented society. We cannot turn the clock back; and I don't believe we can or should suppose that a society run according to strict religious principles would be happier or easier. Traditional Muslims can and do argue that the muddle and fragmentation of western societies indicates that only Islam is able to weld a cohesive society together in our present chaos. But it is not as though there is a single clear system of Islamic government that can be persuasively presented to the world; and the difficulties Muslim legal scholars often have about the limits to freedom of public religious diversity leave a question about how much of our understanding of human rights is compatible with a strict Islamic legal system. If Muslims are right, at least some of our assumptions about human rights may be wrong.

But what the dialogue with Islam has done is to remind people in our Western world that not everyone in the world simply takes for granted the same 'rational' and secular basis for social life. And if we disagree with the Islamic analysis, what have we to offer in its place as the basis for a moral society? I want to suggest two areas in which Christian faith makes a proposal of potentially central importance about the nature of the world we live in, in the hope that this may stir up some proper discussion of the limits of secular thinking in social administration and policy and may open up our social context to some wider and more lifegiving forces. This is not an attempt to force Christian faith on anyone or to suggest that it should be backed by law; it is just to suggest that without some of these elements being taken completely seriously by governments of whatever complexion, our developed economies will never secure anything like justice or stability.

Here is the first of these principles. Christianity teaches that each person is created by God with a distinct calling and capacity. For the Christian believer, human dignity - and therefore any notion of human rights - depends upon the recognition that every person is related to God before they are related to anything or anyone else; that God has defined who they are and who they can be by his own eternal purpose, which cannot be altered by any force or circumstance in this world. People may refuse their calling or remain stubbornly unaware of it; but God continues to call them and to offer them what they need to fulfil their calling. And the degree to which that calling is answered or refused has consequences for eternity.

This means that whenever I face another human being, I face a mystery. There is a level of their life, their existence, where I cannot go and which I cannot control, because it exists in relation to God alone - a secret word he speaks to each one, whether they hear or refuse to hear, in the phrase from the prophecy of Ezekiel. The reverence I owe to every human person is connected with the reverence I owe to God's creative Word which brings them into being and keeps them in being. I stand before holy ground when I encounter another person - not because they are born with a set of legal rights which they can demand and enforce, but because there is a dimension of their life I shall never fully see, the dimension where they come forth from the purpose of God into the world, with a unique set of capacities and possibilities. The Christian will have the same commitment to human rights and human dignity; but they will have it because of this underlying reverence, not because of some legal entitlement.

It means that there are no superfluous people, no 'spare' people in the human world. All are needed for the good of all. Human failure is tragic and terrible because it means that some unique and unrepeatable aspect of God's purpose has been allowed to vanish. As the great Russian novelist Boris Pasternak makes one of his characters say in Doctor Zhivago, we can easily forget how the empires of the ancient world simply assumed that vast numbers of human beings could be sacrificed and slaughtered without a second thought; but the Christian gospel declares that there is nothing more Godlike and precious than a single human person.

It means therefore that a human person is worth extravagant and lasting commitment. A human being deserves complete attention and care whether rich or poor, whether they will live for a day or for six decades. It is typical of Christian practice, for example, that the dying receive expensive care, that those who do not have productive mental capacities as we usually understand them are treasured - and that children and even the unborn are regarded with respect. And it is also typical of Christian practice when it is vital and energetic that people feel able to make the lifelong commitment of marriage to each other - because the beloved person will never be completely understood or 'captured', even in decades of relationship. The transient force of sexual attraction is in this way transfigured by a sense of the uniquely personal, and something radical and exciting becomes possible. Our crisis in sexual morality in the developed world is not just about a failure to keep rules, but about a loss of the sense of personal mystery and the calling to explore someone else's mysteriousness for a lifetime.

It means that no-one's value is ever measured simply by how successful or how productive they are. There will always be something precious that does not need to be proved by success. There will always be something that escapes what society thinks and expects. At the highest this may mean the special calling of the artist; but it also means the respect and care given to all those who do not fit into the expectations of an increasingly impatient and demanding culture, with its obsessive overwork and consequent stress. The Christian vision of persons who are related to God before anything or anyone else represents a way of truly valuing work and patience, but also of valuing leisure and the capacity to receive as well as give.

If our developed societies are mar ked by the tendency to ignore the uniqueness of individuals, to load more and more demands for work and measurable production on to them, to glamorise success and despise failure and to turn sex into a recreation instead of lasting creative partnership, the Christian will say: 'All this is a predictable result of abandoning the belief that each person is the work of God.' And we can go further than this - because God's creation is wider than the human race. What is true of persons is also true of things. The Greek theologians of the early Church sometimes spoke of each element in the material world carrying a 'word' from God, revealing an aspect of God's life and wisdom. If we believe this, we shall not be inclined to treat the world around us as if it were just a quarry for us to take what we want and exploit it. In the sphere of thinking about ecology, the crisis of our environment, we are now more than ever conscious of the need for something like a religious perspective to be brought back into our attitude to a world which is not ours but - once again - is related to God before it is related to us. In the Bible, God calls the world good even before human beings are in it.

All this is a substantial enough picture of what Christian faith brings to our attitudes to social life. And thus far it is still quite close to what a Jew or a Muslim or a Hindu might say, despite its clear foundation in the words of the Bible. These are ideas which people of many faiths can share and work on together in society. But there is an extra element brought by Christianity to the analysis of a good society, and this is the second point I want to underline. The New Testament describes what happens when human beings are brought into relationship with Jesus Christ by faith as a community in which everyone's gifts are set free for the service of others. The community that most perfectly represents what God wants to see in the human world is one where the resources of each person are offered for every other, whether those resources are financial or spiritual or intellectual or administrative. This is the pattern of the Body of Christ as St Paul defines it. It is not only that the least and apparently most useless still has the dignity of having a gift and a purpose; it's also that everyone is able to give to others, to have the dignity of being a giver, being important to someone else. Instead of just a static picture of everyone having dignity, the Christian vision is dynamic - everyone engaged in building up everyone else's human life and dignity.

Such a vision bears very directly on the question of motivation. The religious language I have been referring to takes for granted a basic attitude of reverence, connected with thanksgiving: what is before us, the human and non-human material of the world, is something mysteriously related to God and thus pregnant with God's gift for us. To interact reverently and lovingly with this human and non-human world is not only to express that basic attitude but also to open yourself hopefully to whatever gift God has for you in this or that circumstance, with this or that aspect of the world. It is both an unselfish approach, concerned that the human and non-human world should be not just what I want it to be but what God has designed it to be, and a self-interested one to the degree that I recognise that I cannot be what God designs me to be without the life of others developing according to God's plan. And the stress in Christian thinking on the active responsibility laid on each person means that whether government or private initiative takes the lead, there is a calling to be involved in the work of setting each other free to respond to the possibilities opened up by God.

The Christian vision is not therefore one in which the person's choice is overridden by a religiously backed public authority - which is why Christianity has a mixed history of relation with political power. It has always been a complex balance. When churches have directly tried to exercise political power, they have often compromised their real character as communities of free mutual giving and service; but when they have retreated in the face of power, they have risked betraying their distinctiveness. Christians are called, it seems, to live out the vision of relationships in the Body of Christ without fear of conflict with the rest of society; because sometimes that living out of these relationships can be unpopular with society. They are not called to impose their vision on the whole of society. If they have a role in the political realm, it is that they will argue that the voice of faith should be heard clearly in the decision-making processes of society. If they fail in this attempt, they may still be able to live with integrity. To pick up a phrase used recently in a meeting of European Christian leaders, the churches do not campaign for political control (which would undermine their appeal to the value of personal freedom) but for public visibility - for the capacity to argue for and defend their vision in the public sphere, to try and persuade both government and individuals of the possibility of a more morally serious way of ordering public life. This year, as we commemorate the bicentenary of the abolition of the slave trade in the British Empire, we have a good example of what this might mean.

But the greatest influence that can be exercised by Christian groups in a complex modern democracy is simply in the messages given by various sorts of behaviour which embody the radical respect I have been talking about. Voluntary activity which conveys this message will have the potential, over a period, to shift what society takes for granted. And whether or not legislation arises from this (which could only happen if an overwhelming majority of a population had been persuaded of the rightness of some change - like the abolition of slavery), the climate will be different and the possibilities of human beings will be differently seen. I have already mentioned the care of the terminally sick and the incurably mentally ill as a clear instance of Christian values being affirmed. The Christian hospice is a singularly powerful example of witness. But in less dramatic ways, a Christian school in which academic success and competitive excellence are balanced by pastoral care for all and the recognition of different gifts among those not academically able, in which there is time for thought, recreation, creativity and enjoyment, will equally communicate something about human dignity that can only come from a serious commitment to the mystery of each person made for relation with God. And the active involvement of congregations in monitoring their commitment to fair trade, as expressed in what they choose to buy and how they bring consumer pressure to bear on issues of production and marketing - this too can be an effective witness. In the UK, we are also developing a variety of simple ways in which individuals and congregations can monitor their environmental 'footprint' - a small but significant contribution to raising general awareness of this question as a moral and spiritual matter.

Quite often, as with the case of environmental concerns, Christian - and other religious - bodies are uniquely well-placed to pick up those causes that have been slow to attract mainstream political support because they do not win votes(the reform of prison conditions is another that has drawn much support recently from churches in the UK). It has to be recognised that the apparently rational and equitable processes of secular democracy are always vulnerable to the requirements of the electoral process - which are, sadly, not always rational and equitable. Large-scale issues about public prosperity dominate these conflicts, and it is hard to find a hearing for other questions of longer-term significance - and longer-term here does not mean less urgent. Churches and other faith groups might be called the trustees or custodians of the long-term questions, because they are trustees of a vision of human nature that does not depend on fashions and majorities.

A healthy democracy, then, is one in which the state listens to the voices of moral vision that spring from communities that do not depend on the state itself for their integrity and meaning - above all the communities of faith. In this lecture, I have been suggesting some of the specific ways in which the Christian model of humanity and the world in relation to God can open doors for renewed political vision; the Christian is not seeking to make the state into a church, but is proposing to the state and to the culture in general a style and direction of common life - the life of the Body of Christ - that represents humanity at its fullest. A determinedly secular society is always in danger of becoming closed upon itself, never really coping with radical criticism, lacking a forum for discussing general moral priorities, reluctant to change.

In contrast to much of Islamic history, Christian history shows a pattern of engaging with society and law from alongside. It has not generally attempted to suggest that the affairs of the state should be directed by religious experts. And that has normally had the healthy effect of making Christians suspicious of any claims by earthly rulers to be religious experts simply in virtue of their position (I have to admit that the attitude of my own church in the reign of King Henry VIII is an embarrassing exception).

Christianity has asked not for licence for its leaders to control society, but for a proper hearing of its concerns and - ideally - a willingness on the part of political leaders to show self-critical honesty and, where appropriate, repentance. The great St Augustine, considering the merits of the Christian emperors of the fourth century, gives a special place to Theodosius I, simply because he was persuaded by St Ambrose to make a public act of repentance after he had ordered a massacre. It is not that the state and the laws of society must represent in all respects the commands of the gospel; it is rather that the state will become a sterile and oppressive thing unless it is continually engaged in conversation with those who speak for the gospel.

That is perhaps the essence of the Christian contribution in the public sphere. It is a voice that questions from a wholly different perspective, the kind of perspective that cannot be generated by corporate self-interest. It is a conversation partner, and what has sometimes been called a critical friend to the state and its laws; it asks about the foundations of what the state takes for granted and often challenges the shallowness of a prevailing social morality; it pushes for change to make the state a little more like the community that it is itself representing, the Kingdom of God.

It does not make the mistake of talking as though politics would bring the Kingdom into being on earth, but it continually seeks to make the promise of the Kingdom more concrete and visible in the common life of human beings, private and public. In short, it tells the state not that it is unimportant or subordinate to some higher earthly power, but just that it is relative in the perspective of God. If a certain degree of shared humility and realism is part of the life of a healthy state and society, that is one of the things that Christian proclamation can offer.

But that, of course, is primarily a negative thing. I would hope that these thoughts have also clarified some of the positives that the gospel brings to bear, especially in its uncompromising insistence that there are no dispensable human beings, no persons who are unimportant to the threefold God who is committed to the world he has made and into which he ahs entered to redeem it.

Finally, all the passion and energy which a Christian may bring to social or political involvement is only an expression of that fundamental disposition and habit of Christians - gratitude for the free movement of God towards creation, first in his decision to make a world at all, and then in his decision to engage with it in love, a love capable even of entering the world of injustice and suffering its effects so as to bring a reconciliation that can reach to the ends of the earth.

This is more than just an affirmation of human rights, more than a commitment to abstract justice. Christians are called to see others and especially others in profound need from the perspective of an eternal and unflinching, unalterable love. So far from Christianity threatening to undermine humanity's freedom and dignity, as some of the Enlightenment's legacy suggests, it establishes that dignity on the strongest possible basis.

If the story of the Bible tells us how deeply God has loved what he has made, the Christian knows that the world in which he or she lives makes the alarming claim to be seen as worthy of that kind of love. We hope and pray that we as believers can respond to this by the strength of God's Holy Spirit; and we proclaim this vision as the firmest possible ground for hope in any imaginable human society, eastern or western, past, present or to come.

Copyright Rowan Williams 2007