Athens, Greece - In 1905 France passed a landmark law declaring a clean break between church and state. Riots erupted and a papal encyclical denounced the act as a "most pernicious error."
Such extreme passions cooled long ago, but the core questions remain as strong as ever. Debates over religion, politics and civic life — and how much they should overlap and interact — are demanding more attention across Europe than at any time in recent decades.
It's no longer just about whether to untangle or preserve the old relationships between secular and spiritual— often only symbolic these days, but still an important stream of revenue for churches.
New fronts are emerging: Traditionalist groups seeking a closer embrace of Europe's Christian heritage, and others predicting that efforts to better integrate Muslim communities will also require new models for religion's role in public life.
"Religion — for good and bad — is reasserting itself as a force in Europe," said Gerhard Robbers, a professor of political and religious studies at Germany's University of Trier. "The period of secularism is coming to an end. A new landscape is emerging."
But in the 25-nation European Union, it's a very uneven terrain, with church attendance ranging from above 50 percent of followers in Ireland and Poland to below 10 percent in Scandinavia.
Several European countries fund churches through a church tax. In Germany, the state-mandated levy runs as high as 9 percent of a person's income tax, and is cited as one reason why more than 100,000 Roman Catholic and Protestants officially break ties with their churches every year.
When the EU expanded in 2004, it inherited a swath of Eastern Europe where churches — particularly the Roman Catholic and Christian Orthodox — have been reasserting their voices in civil affairs after being sidelined for decades by communism. Two of the other newcomers have deep church-state bonds: Malta with Catholicism and the Greek-speaking zone of divided Cyprus with the Orthodox church. Two more predominantly Orthodox nations, Bulgaria and Romania, will enter the EU fold in January.
In Poland, another new EU member, top government officials have been guests on a popular Catholic radio station, Radio Maryja, whose ultraconservative views and commentary on political affairs and relations with Jews have drawn criticism from the Vatican.
Many of the new EU states were among the strongest voices in the unsuccessful effort to include a mention of God or Christianity in the EU constitution, which was mothballed — at least temporarily — after rejection last year by Dutch and French voters.
German Chancellor Angela Merkel said this year that "Christianity has formed Europe in a decisive way" and should be reflected in an eventual constitution. But her party, the Christian Democratic Union, has tried to position itself as a centrist group whose name only echoes the once-powerful Christian political movements that rose across Europe following World War II.
In a joint declaration last month in mostly Muslim Turkey, Pope Benedict XVI and the spiritual leader of the world's more then 250 Orthodox, Ecumenical Patriarch Bartholomew, stressed the need to "preserve Christian roots" in European culture while remaining "open to other religions and their cultural contributions."
Such messages resonate with some rightist political groups, such as Austria's Freedom Party or the British National Party, which see pro-Christian platforms as a way to tap into public anxiety over growing Islamic communities and Turkey's bid for EU membership.
Britain could become an important barometer.
Christian groups, including the Evangelical Alliance and the upstart Christian Council of Britain, have sent out signals they will actively mobilize voters in the next general election, expected in 2009. Meanwhile, discussions over religion and public life are moving increasingly into the foreground — with sometimes divisive results.
In November, a British religious think tank, Theos, published a survey in which 43 percent said religion is not a force for good in society and 39 percent said Christianity does not have an important role to play in public life. The British Humanist Association called it a ringing "statement of disillusion with religion," while Christian groups took heart from the majority who had favorable opinions on religion in the public sphere.
"The crisis that splits Europe is of a cultural order. Its Christian identity is being diluted," said a statement from high-level Roman Catholic and Orthodox envoys following a three-day meeting in Vienna in May.
But the general trends appear to be toward separating church and state by dismantling or weakening their few remaining official links.
In Greece, the head of the powerful Greek Orthodox Church, Archbishop Christodoulos, said he would not object to a "velvet separation" which would preserve the church's tax breaks and other privileges but eliminate clergy from presiding at official events such as the swearing-in of political leaders.
A poll in January by the Institute for Greek Public Opinion found nearly 60 percent favor ending the official status of the Greek Orthodox Church.
In Britain, where the monarch is titular head of the Church of England, Anglican clergy have been steadily dropping the practice of including prayers for Queen Elizabeth II. It's another small but noticeable crack in the church-state structure, which could come under further strains if the throne passes to divorced and remarried Prince Charles.
"We are witnessing post-Christian Europe taking shape," said Jonathan Bartley, co-director of Ekklesia, a London-based group that examines religious and social trends. "The remaining alliances of religion and governments don't make sense anymore, in many people's eyes, and they are coming apart."
What may emerge in coming decades, experts say, is a greater presence of religion-oriented groups seeking to shape public policies as Europe becomes more culturally and religiously diverse.
"Whatever the form, such dialogue might be able to generate new insights and policy proposals which cut through the antagonisms in the international debate," German theologian the Rev. Konrad Raiser told a World Council of Churches gathering. "We live in a divided world and the churches share in this division."