Twenty-five years ago, almost one and a half million Christians lived in Iraq. Now there are around a quarter of a million, and after years of war and communal violence many of them have been displaced from their ancestral homes. Can anything be done to reverse this trend toward extinction? Stephen Sackur speaks to Archbishop Bashar Matti Warda of Erbil, home to the largest remaining Christian community. In a country and a region where Christianity has deep roots, does it have a future?