In debates about immigration a crucial issue is the moral and political status of borders. Do we think borders are good or bad, a necessary evil or a moral necessity? My contention is that those who argue for open borders undervalue a sense of place and the integrity of nations like Britain and Australia as political communities; but those who argue for closed borders overvalue the likes of Britain and Australia as political communities.

Instead, I will suggest we need a way of valuing our particular political communities in relation to other nations, and ultimately in relation to God, and that such a framework will enable us to make appropriate decisions about how to respect and value existing citizens and fulfil our duty of care to the refugee and vulnerable stranger from outside our borders.

Mass migration is a central feature and consequence of globalisation and will continue to be a major factor of social, political and economic life for the foreseeable future. Mass migration is, of course, not a new phenomenon, but it is morally and politically problematic for two key reasons.

It is politically problematic because it involves crossing borders between different nation-states and therefore it involves the re-negotiation of the fundamental political and legal status of the individual concerned.

It is morally problematic because current immigration policies adopted by all nation-states favour the needs of the strong (the existing members of a polity) over the weak (asylum seekers and vulnerable economic migrants).

The underlying options shaping the political debate and policy response to mass migration seem unable to cope with either reality. We seem to be forced either to prioritize the needs of the strong, and so have closed borders with tight immigration controls and large-scale deportation of illegal immigrants in the hope that this will deter further migrants; or we prioritize the needs of the weak and have open borders.

I want to argue that a Christian account of how we think about the duty of care we owe to our neighbours, near and far, is a much more robust, constructive and realistic way of framing a response to the issues mass migration challenges us with.

But let me begin by analysing the two primary moral-philosophical responses to mass migration, before putting forward my own proposal.

Liberal utilitarians argue that democracies, in principle, owe an equal duty of care to all humanity and by implication, that borders should, in principle, be open. Peter and Renata Singer, for instance, argue that immigration policy in general and refugee policy in particular should give equal consideration to the interests of all those affected. And where the interests of different parties conflict (that is, where the needs of existing citizens conflict with the needs of a refugee) priority should be given to those with the most pressing claim to have their needs met.

Now, admittedly, no one advocates completely open borders, and even utilitarians recognise limits to freedom of movement and how this freedom can conflict with other rights. They recognise that there is a basic problem which restricted borders are a means of addressing - that is, the need to balance the rights of existing members of a democracy with the human rights of every individual to freedom of movement. They also recognise the need to keep out criminals and those who present a danger to existing citizens and the integrity of the polity.

But for advocates of open borders, borders are morally wrong in principle even if they are a necessary evil in practice. What matters to those who argue for open borders is not a particular political community but the rights of the individual. Border controls, in their view, place a higher value on the existence of one particular community - say Australia - than on the value of an individual and their human rights. For them borders should allow free passage of individuals from one place to another, while acting as a filter for violent and criminal individuals.

From a Christian perspective, this might all seem right and proper - we should, after all, value the image of God in all humans, and respect for human rights seems a good way to do that. But while those who argue for open borders are deeply concerned about how we may respect everyone's humanity, they abstract love and respect an individuals' humanity from the question of what it means in practice to love and respect this particular person in this particular place.

From the Christian perspective, there is no such thing as a love of humanity in general, but only a love of particular persons in particular places. This love is itself situated within concentric circles of relationship beginning with the family and ending with humanity as a whole. Truly loving relations necessarily involve particularity, limits and points of exchange at both an individual and communal level.

The particularity of persons is, to a large extent, constituted by their place - that is, their social, economic, political and historical location in creation. These places and their limits form the basis and pattern of the relations of giving and receiving that constitute what it means to be human in the image of God.

The parable of the Good Samaritan is particularly instructive here. This parable is often understood as justifying a universalistic ethic of unconditional love - that we should love anyone and everyone. However, while the parable suggests aid knows no boundaries, the extension of solidarity is particular: care is given by one person to another. The so-called "good Samaritan" responds to someone he finds nearby, not some generalised or abstract bearer of rights who exists nowhere and everywhere.

The one in distress is presented as a fleshly body to be hosted through costly personal involvement. To abstract or objectify this particular body and so pass on by without really encountering them is a sin. As Oliver O'Donovan argues:

Unlike the utilitarians and deontologists who call us to love an indistinct "humanity," a properly Christian view calls us to love particular persons who are located in particular places. Thus the problem with seeing borders as filters and migration as simply a question of individual freedom of movement is that it fails to value the on-going integrity and worth of one's place - Britain - and that migration does change places for better and for worse, and that people are right to be concerned about the changes it will bring. Lack of attention to this concern and love for one's own place feeds into racist rhetoric and a nationalistic exclusionary nostalgia.

By contrast, communitarian philosophers argue that borders are not only necessary in practice but are morally required. Michael Walzer, for instance, insists that entrance policy goes to the heart of political sovereignty and the ability of a community to sustain a common life. He argues that the primary duty of care that members of a political community owe to each other is the communal provision of security and welfare. Should the numbers of refugees and migrants ever threaten the provision of security and welfare, there is a strong case for refusing entry.

So here the real question is at what point do the numbers threaten security and welfare, and therefore at what point should the fences be higher or lower in order to protect the maintenance of the existing community.

But surely, from a Christian point of view, the cultivation and maintenance of a distinctive national life cannot be an end in itself. Rather it must be subordinated to the concern for an international order of justice and freedom. However, this order can only begin in particular communities, which then form unions with other nations, such as the European Union.

There ought, therefore, to be no inherent or necessary conflict between the duty of care to migrants and refugees and the duty of care to existing citizens. Rather, the duty of care to migrants and refugees must be ordered in relation to pursuit of the common good, which itself must be ordered in relation to the universal good of humanity.

The true end of humans lies neither in family, nor in a particular culture or nation, nor in some kind of worldwide polity, but in communion with God. The way we order the relationship between the needs of migrants and the needs of existing citizens needs to be set within this bigger picture.

So it is my argument that we need to see borders as a face that we, as a nation, present to the world. A face is what says that I am somebody who deserves respect, that I am not simply a piece of land to be bought and sold or a thing to be used for a time.

It says that I have a personality and a history and a way of doing things, but also that I am made for relationship and without coming into relationship with others who are different from me, then I do not grow.

Ultimately, it says that I am a face who seeks to look upon the face of God and who finds the face of God reflected, not in the faces of the strong and powerful, the skilled and the economically capable, but in the faces of the orphan, the widow and the refugee - and this is who God bids invites me to be hospitable.

To think of borders in terms of the metaphor of the face re-orientates us to see there is value to be placed upon the existing community, but the existing community is not an end in itself. It is only fulfilled as it moves beyond itself and comes into relationship with those around it.

Borders are a means of framing and structuring this relationship, and orientating places like Britain to the rest of the world in a way that presents an enquiring, confident, hospitable face rather than a closed, incestuous, hostile face that abjures its responsibility to the poor and vulnerable.

By understanding a nation's borders as a face, we can give proper attention to the histories and customary practices that shape our existing national life. But it also requires that we move beyond mere humanitarian concern or isolated charity, and toward authentic long-term relationships, and it is this that enables strangers to become citizens.