When 10 new countries enter the European Union on May 1, millions of Christians will bring their faith with them, hoping the prosperity membership will bring will not lead to secularisation.
From Poland and Slovakia in central Europe, to Lithuania in the Baltics and the Mediterranean island of Malta, the new EU entrants all have more people practicising religion than current EU members.
"In the 10 new member states, the number of believers is much higher than in the majority of western countries," Tadeusz Szawiela, a religious sociologist at Warsaw University told AFP.
Even current EU members with large numbers of Catholics or Protestants, practise their faith less than their eastern counterparts.
While 31 percent of Dutch people, for example, say they are Catholic, only eight percent of them are practising, while of 21 percent of stated Protestants, only nine percent go to church.
France and Belgium, countries with large Roman Catholic populations, have to bring in priests from central Europe.
And no more so than from Poland, the country of Pope John Paul II, which in 2000 accounted for 12 percent of European priests and one out of every 20 Catholic priest in the world.
Fifteen years of economic and political transformations since the fall of communism have not changed Poland's devoutness, with more than 90 percent of Poles saying the are Roman Catholic, with 50 percent practising regularly.
Only the Maltese are more Catholic than the Poles, with 95 percent of its 395,000 inhabitants saying they are Catholic, with 65 percent practising.
Slovakia has gone through a religious revival, after 40 years of persecution by the communist authorities, with the number of people belonging to a Christian religion, mainly Roman Catholicism, increasing by 11 percent in 10 years, to 84 percent of the population in 2001.
At the same time, religious worship has dropped off in the Czech Republic, by 12 percent to 32 percent.
Churches also packs a political punch in the region, with most having thrown their weight behind their countries' EU membership.
In Lithuania, where 70 percent of the population say it is Roman Catholic, priests came to the help of the government from the pulpit, after a slow start to a May, 2003 referendum on EU membership.
The Polish Roman Catholic Church, although reticent at first, also strongly backed the leftist government of Leszek Miller on EU entry.
Now Polish bishops have called on compatriots to turn out and vote for "Christians and Catholics" when the country takes part in European Parliament elections for the first time in June.
Churches, and Pope John Paul II in particular, have made their voices heard in talks on a European Union constitution, demanding a reference to God in the treaty.
But in the run-up to EU enlargement religious leaders have expressed fears that people might lose their faith as they become richer and more attached to the consumer society.
"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," sociologist Szawiela said.
"If wealth comes suddenly, secularism will follow. If, however, the standard of living improves gradually, which will probably be the case, the churches should keep their faithful," he said.
Marcin Przeciszewski, the editor in chief of the Catholic news agency KAI, said fears of a drop-off in church attendance after the fall of communism had proved to be unfounded.
"The most pessimistic scenarios, under which, after the fall of communism, the churches in Poland would be emptied, turned out to be wrong," he said.