European countries that were stalwarts are turning away from Catholicism.
Whoever takes the helm of the Vatican after the shock resignation of Benedict XVI will inherit a problem on his own doorstep.
Home to more than a quarter of a billion Catholics, the headquarters of the Holy See, a wellspring of doctrine and a source of manpower that has helped make converts throughout the world, Europe is the church's heartland.
Except for half a dozen early Popes born in North Africa or Palestine, Europe has provided all the pontiffs over nearly 2000 years of papal history. Of the 118 cardinals called to next month's conclave to choose a new Pope more than half will be from Europe, 21 from Italy, the largest number from any single country.
But Catholicism in Europe is in trouble. Countries that were Catholic stalwarts have pushed through laws liberalising abortion, widening access to contraception, permitting divorce or civil partnerships, secular teachings in school and authorising gay civil unions, even marriage. In many nations, church attendances are plummeting. Europe may retain its clout within the Vatican, but its share of the world's tally of Catholics has fallen to below a quarter, according to official figures.
In the 16th century, anger at corruption gave birth to Protestantism. The present crisis - less sensational but almost as draining - can be traced back nearly half a century.
Some cite hostility to bans on contraception set down in the 1960s by Pope Paul VI, discord with the Vatican's animosity towards homosexuals and scandals over sexual abuse of children by renegade priests. Others point to conservatism that is out of touch with modern urban life.
"This church has remained stationary for 200 years. The Vatican has not allowed the vitality and imaginative power of the church in the Third World and in Latin America to emerge. The houses of God in Europe are large, but they are empty," the German daily Suddeutsche Zeitung, published in an editorial. Berlin's leftwing daily TAZ announced the Pope's resignation with the headline, "THANK YOU, GOD."
In Germany, record numbers of people are leaving the church, according to figures for the Kirchensteuer, or "church tax" - a levy of between 8 and 10 per cent of one's income tax that salaried workers pay to the religion of their choice.
In a population of nearly 82 million, one third of Germans are registered as Catholic and another third as Protestant. In 2011, 126,488 people formally de-registered as Catholics, a 40 per cent increase on the previous year.
In December, the German bishops' conference issued a decree forbidding confession, communion, confirmation, becoming a godparent and even anointing of the sick, unless the individual's life is in danger, to anyone who leaves the church.
"If the person who has left the church has not displayed any regret before their death, a religious burial may be refused," the decree added.
A liberal Catholic movement, Wir Sind Kirche (We Are Church) bitterly attacked the move.
"Instead of tackling the reasons why people are leaving the church in large numbers, this bishops' decree is a threat and is not going to motivate people to remain loyal or to join the community of those who pay their church tax," it said.
In Poland, where over 90 per cent of the population are Catholic, four out of 10 attend Sunday Mass according to the Institute of Statistics of the Catholic Church. But this figure for 2011 represents a fall of 10 per cent over 1980.
In Ireland, the church's traditional clout in politics has been crippled by a reports into clerical sexual abuse and an outcry over the death of Savita Halappanavar, who died from septicaemia after being denied an abortion while she was miscarrying.
In France the Lower House of Parliament approved a law permitting gay marriage and adoption after a debate that saw mass rallies by pro- and anti-factions.
The bill goes to the Senate in April. In Britain, the House of Commons voted overwhelmingly in favour of a same-sex marriage earlier this month, and it is expected to pass into law within the next six months.
According to Frank Cranmer, a Fellow of St Chad's College Durham in northeast England, religions are facing problems of legitimacy.
"There was a time when people were at least vaguely respectful of clergy of whatever denomination - but I don't think they are any longer," Cranmer told the Herald.