That a gospel of love can so easily be used to legitimise political injustice or social enmity is the paradox which has torn the tattered canvas of Irish history into shreds. Familiar though we are with the biblical analogy of motes and beams, the practice of Christianity in Northern Ireland - as often perceived from mainland Britain - is something we are often tempted to condemn.
John D Brewer's excellent study on the sociological implications of four centuries of anti-Catholicism in Ireland does, however, remind the English of their historical responsibility. Similar sentiments have forged our constitutional settlement (the impossibility of a Catholic monarch, despite the claim of blood), our cultural mythology (burning the Guy on 5 November), and our national identity. Indeed, at the close of the 19th century, Britain proudly stood for three things: Protestantism, free trade and Empire. And God - as the old joke goes - was an Englishman. Surely acknowledgement of our own impaired vision is necessary before attempting to correct that of others.
Professor Brewer realises this, in the spirit of the mote and the beam. It is as a (Protestant) "Christian sociologist" that he writes. Not denying the existence of anti-Protestantism, Brewer suggests persuasively that it has never "permeated the social and cultural structures of Northern Ireland so systematically".
His purpose is to challenge a community's perception of itself, and thereby of their neighbours, not simply to repeat the familiar two-sided tragedy. As such, it is a partisan book - necessarily so, as it confronts ideological preconceptions on their own terms. Yet the work is infused throughout by a reticence to judge, and a firm view on the past as a prologue to future possibility rather than a window on suffered wrong.
In the nervous climate of Northern Ireland's new start in 1999, such research is refreshing. Her prophets have usually been the Paisleys, unable to see the future but "through the prism of the past" and little more than the second-hand salesmen of historical myth.
Brewer knows the same history, but reads it with an understand- ing that the perpetuation of "socio-ethnic tribalism" offers no future. He glances back the better to look forward.
The result is a glimpse at "unremembered" segments of Ulster history, in which are found alternative voices to those of violence or prejudice. Those of the leaders of the Belfast dock strike in 1907, for example, in which dockers found common cause "not as Catholics or Protestants, as Nationalists or Unionists, but as Belfast men and workers".
My Ulster grandfather, the staunchly Protestant auctioneer of the little town of Raithfriland in Co Down, gave shelter to Catholics in the bloody "troubles" of 1918-20 on the basis of similar sentiments. Later they underpinned the determination of Terence O'Neill, a family friend and former Unionist Prime Minister, to "break the chains of ancient hatreds" and embrace a pluralist politics. In 1965, the General Assembly of the Presbyterian Church begged "forgiveness for any attitudes and actions towards our Roman Catholic fellow countrymen which have been unworthy of our calling as followers of Jesus Christ".
The picture which emerges is of a different Northern Ireland than that of Drumcree, and a different Christianity than that of Free Presbyterianism. It offers the possibility of a new future led by the likes of Trimble and Hume. What this future does rely on, however, is little less than the transformation of identity; the transcendence of social boundaries construct- ed along the lines of 16th-century theological differences.
Four hundred years of opposition have left Unionists feeling under siege from the nationalist community within, the Republic to the south, and abandoned by the Britain they have sought to defend. The twin fears of threat and isolation, legitimised by a divine mandate, prove resilient foes. If ever there was a time for the resurgence of social and political liberalism within Ulster, it is now.
Last year was unlike any other in Northern Ireland's history - Good Friday and Omagh, the best and worst moments of a generation. The loaded gun still remains on the negotiating table and a familiar mistrust hangs over the new Assembly. But as the politicians continue to struggle through the difficult issues of decommissioning, of amnesty, of coalition, old ways of thinking need to be disarmed and mindsets decommissioned.
One thing is clear: this ideological ceasefire represents the greatest challenge for Northern Ireland into the millennium, and one in which, perhaps, the pen is more powerful than the gun.
The reviewer is leader of the Liberal Democrats