At regular intervals, our news headlines are dominated by what is undoubtedly a very emotional story, but one which has massive implications for our future peace: we see desperate people filling boats in the Mediterranean or lorries at Calais; migrants risking life and limb to get into a new country and find accommodation and employment, hope for a future worth looking forward to.

It’s a scene which demands an answer to hard questions: is the nation state, the main way we go about organising travel, trade, and assuming identity and belonging, ethically defensible any more?

Is it fair that so many of life’s opportunities depend upon having in one’s possession such a simple thing as a passport?

Or has this system, however frail, evolved for a purpose – that it’s the best way still of carrying out the complicated task of controlling and regulating the movement of people?

Seeking just such an answer are two Christians – Professor Nigel Biggar and Dr Stephen Backhouse – and a Muslim – Professor Sajjad Rizvi – who, in debate with Mark Dowd, begin by not seeing eye to eye on what the nation state is for.

Image courtesy of Irish Defence Forces via flickr.com ©©patriotism