Germany's Roman Catholic Church, already grappling with the fallout from a child sex scandal, fears losing more followers -- and financing -- because of public anger over a big-spending "bling bishop".
For the past week the Bishop of Limburg, Franz-Peter Tebartz-van Elst, has generated damaging headlines after the cost of his extravagant new residence complex blew out to at least 31 million euros ($42 million).
The 53-year-old has been summoned to the Vatican for a decision on his fate, and was set to meet on Thursday with humility advocate Pope Francis, who has called for a "poor Church for the poor".
With many faithful in the German diocese in open revolt over the lavish bishop's palace and its 15,000-euro bathtub, there has been a sharp increase in local registered Catholics formally leaving the Church.
If the exodus in the ancient town of Limburg were echoed on a national scale, observers say it would be a severe blow to the Church -- especially in a country where the faithful provide the bulk of its funding.
"I've never seen such a wave" of people quitting the faith, Ruediger Eschoffen, an official in charge of Church registrations in Limburg, was quoted as telling the newspaper Frankfurter Neue Presse.
Germany has a religion tax, and taxpayers must declare whether they are Catholic, Protestant or non-religious. People are however free to opt out and stop paying the so-called "Church tax".
Last year 295 Catholics in Limburg, in the central state of Hesse, officially left the Church, said Eschoffen. But he said the figure shot up to 29 people in a single day on Monday, after 18 left on Friday and 20 on Thursday.
Germany's roughly 23 million Catholics paid 5.2 billion euros to the Church in 2012 in religious taxes, its main source of income in the country. The state tax amounts to an eight to 10 percent addition to payable income tax.
The money pays for the operating expenses of the clergy, but also for hospitals, kindergartens and other welfare organisations.
The German Catholic Church, just as in Australia, Canada, Ireland and the United States, was already hit hard by a paedophilia scandal, which erupted in the country between 2010 and 2012.
The revelations sparked a flood of people quitting the Church, with 180,000 leaving in 2010. By 2012, the figure had dropped to 118,000, a lower level than in 2009 before the abuse charges came to light.
'A loss of confidence'
The latest scandal spells a real risk for the Catholic Church, said Detlef Pollack, a sociologist researching religion and politics at the University of Muenster.
Tebartz-van Elst, dubbed by local media the "bling bishop", is also accused of giving false statements in court in a case centred on an expensive flight he took to India to visit poor communities.
"Many people say they do not want to continue to (financially) support the Church if it is to satisfy the appetite for luxury of a bishop," Pollack told AFP.
Several German dioceses have announced plans to report their assets to avoid suspicions about their lifestyle.
Beyond the financial risk, the Church fears a loss of confidence in an institution that still plays an important role in society, especially in the mainly Catholic south.
Chancellor Angela Merkel, daughter of a Protestant pastor, is also worried. Her spokesman Steffen Seibert on Monday expressed "the hope that there will be an answer for believers, for people's confidence in their Church."
But Pollack said: "A lot of confidence has been lost."
"The Bishop of Limburg can no longer fulfil his role in his diocese. The best thing for him would definitely be to renounce his post."
Such a move would be difficult however within the Catholic Church, said conservative daily Die Welt.
"Catholic bishops are neither managers nor politicians," it said. "They do not derive their spiritual and temporal powers from the confidence of a supervisory board or the electorate, but from God."
It added that "quitting over real or perceived wrongdoing is a widespread and accepted practice in politics and business. They are the rules of the game. Until now, this was not the case in the Church".