Even in Western EU nations with large numbers of people who identify with a particular religious denomination, religious practice is often less common than in many of their Eastern counterparts. Almost a third of the Dutch, for example, say they are Catholic -- but only 8 percent of those say they are churchgoers. Among Dutch Protestants -- about one in every five citizens -- 9 percent are churchgoers.
The majority Catholic populations of France and Belgium are net importers of Catholic priests from the East. Poland, the native country of Pope John Paul II, supplies 12 percent of Europe's priests and one out of every 20 priests worldwide.
As the day (1 May) draws near for 10 new countries to join the European Union, scholars are looking into what impact accession may have on the religious climate of Europe.
The Reverend Stephen Plant is a lecturer in theology at Cambridge University. He tells RFE/RL that from one religious perspective, there really are a number of Europes, not just one.
"You can't really speak of Europe as a whole because in Catholic countries, in Protestant countries, and in Orthodox countries, the picture seems to change and alter depending upon which particular brand of Christianity, so to speak, is in the ascendant," Plant says.
But, Plant says, Europe overall has responded to modern times differently from other parts of the world. While religion remains a major factor in the countries of Latin America, Africa, and Asia, Europe has become less religious the more developed it becomes.
Plant says this trend is likely to continue, in that the established countries of the EU are more likely to influence the religiosity of the new members rather than the other way around.
"When we come to look at the enlargement issues in Europe, I think that what we will see is that countries that were formerly on the other side, the Eastern side, of the Iron Curtain, will come quite quickly to resemble countries on the Western side. And we're already seeing this in, for example, the Baltic states, which very closely resemble patterns of religion in northern Europe," Plant says.
In recent months, one religious issue has held the attention of old EU members and newcomers alike. That is the question of whether a religious declaration should be embedded in a European constitution now being negotiated. How the debate finally is resolved probably will be instructive about the religious climate likely to follow.
Ben Crum, a research fellow at the Brussels-based Center for European Policy Studies, specializes among other issues in democratic policy and constitutionality. He has followed from the start the EU's effort to develop a constitution. He tells our correspondent that a number of countries -- both old and new EU members -- pushed hard for language in the document that would recognize Europe's Christian heritage.
"There was a consistent movement of a number of people [in the EU leadership], especially with a background in the Christian Democratic Party groups, that lobbied for explicit references to religion and even more so to the Christian religion in the constitution," Crum says.
A portion of the draft constitution lists European values. It mentions the rule of law, democracy, and freedom, but is silent on religion. Another portion recognizes churches and other groups and non-governmental organizations as bodies that will contribute to EU deliberations. The chief remaining area of religious controversy, Crum says, is the preamble.
"The debate in the end focused on the preamble. A preamble, of course, has always had a kind of proclamatory function -- the function of announcing the status of the constitution and where do we come from and where do we want to go as the European Union. There the initial draft followed a line of religious abstention. There was no reference to anything of the kind. And that really provoked a very sharp reaction, not only from those who had consistently been lobbying for a Christian phrase, but also from the mainstream Christian Democrats, who did expect something of religious history and its importance in the making of Europe to be there," Crum says.
This dispute seems also to have been resolved.
"And in the end, a compromise was found in a very broad formulation that refers to the intellectual history and the general religious interrelation that is part of the heritage of Europe,” says Crum. “The specific line now is 'drawing its relation from the cultural, religious, and humanist inheritance of Europe, the signs of which are still present in its heritage and have been imbedded within the larger society.' "
Crum says his personal forecast is that the members of the enlarged EU will accept the preamble's religious reference as drafted. And his personal opinion as a student of constitutions and of modern European development is that they will be right to do so.
"I don't have any problem with the present formulation. I think that religion is part of the wider societal heritage of Europe. And for sure, Christianity has been the most prominent religion. The question is whether you want to highlight that in a political document that should be more forward-looking than looking to the past," Crum said.
To Cambridge theologian Plant, how the new mix of religious traditionalism and secularism in the EU will affect individual countries will be largely a function of their level of nationalism. In new member Poland, he says, to be a Pole is to be a Catholic. Poland in this way, he says, is like Italy and Ireland.
A religious sociologist, Tadeusz Szawiela of Warsaw University, says he thinks a significant influence will be the pace of the growth of prosperity. Agence France Presse news service quotes him as raising this question: "[Strongly religious] countries like Poland, Malta, Slovakia, or Lithuania -- will they follow the example of Ireland, where we have seen a decrease in religiousness, once the traditionally Catholic country has gained prosperity?"
Szawiela concludes that sudden wealth is likely to foster secularism. But if prosperity creeps up gradually on the new member countries, which he says is more likely, then the churches probably will retain their faithful.