By Philip Pullella and Sarah Marsh
FREIBURG, Germany (Reuters) - Pope Benedict urged Catholics in his native Germany on Sunday to close ranks behind him rather than demand reforms or leave the Church, a staunchly conservative message that some who came to hear him found frustrating.
Addressing about 100,000 people during mass at a small airport near the southwestern city of Freiburg, he said the sometimes fractious Church needed to unite around him and the German bishops.
"The Church in Germany will continue to be a blessing for the entire Catholic world if she remains faithfully united with the successor of St Peter," he said, referring to himself.
His third trip as pope to his native country has been his toughest, met by protest over sex abuse scandals, reform calls from Catholics who view his conservative stand as outdated and hopes from Protestants for closer ecumenical cooperation.
The pope flew back to Rome from Freiburg in the early evening.
Benedict has closed the door on changes to the Church's opposition to gay marriage, married clergy or women priests, and has indicated he will not ease restrictions on divorced Catholics who have remarried outside the Church.
From highly secular Berlin to former communist Erfurt to Catholic Freiburg during this four-day trip, he has hammered home his view that the Church cannot change merely to suit the whims of the times.
Polls say many German Catholics disagree. A record 181,000 officially quit the Church this year -- for the first time more than joined and more than those quitting Protestant churches.
Some worshippers told Reuters they were happy to have an opportunity to attend mass celebrated by the head of their Church but were frustrated by his opposition to change.
"I had hoped he might rally people more to the Church, especially young people," said Martine Kircher, 50, who brought her four children from Heidelberg to see the pope.
"But he didn't show a path of renewal," she said. "Instead he seemed to be rowing back to the old values."
The fact German Catholics could both call for reforms and still turn out in large numbers for a papal mass "shows the Church in all its ambivalence," Rev Bernd Hagenkord, head of Vatican Radio's German service, told German television.
"It is a very mixed church," he said.
Even in an increasingly secularised society, the Catholic and Protestant churches are major institutions in Germany.
About a third of Germans are Catholics, a third Protestants and a third unaffiliated or members of minority faiths such as Islam and Judaism. Members pay a church tax that helps fund extensive social, educational and health programs.
Polls show that many Germans, thrilled when he was elected in 2005, now see the pope as obstinate and out of step with how his homeland has developed since reunification in 1990.
Office worker Holder Gasch, 37, one of those in Sunday's crowd, told Reuters: "The Church needs to be more progressive in its attitude toward homosexuality and women."
Several lay Catholic leaders and even some bishops have urged the pope in recent weeks to allow some reforms, a request he appeared to reject on Saturday when he said that without a renewed faith, "all structural reform will remain ineffective."
The issue of sexual abuse of children by priests has been in the background through most of the trip. At the start of the trip the pope said the Church was made of "good fish and bad fish" and urged Catholics not to leave because of the scandal.
The Church in Germany has received almost 700 requests for compensation for victims of sexual and physical abuse, while a victims' association estimates that more than 2,000 people were mistreated by Catholic priests in recent decades.
Benedict held a surprise meeting on Friday in the city of Erfurt with victims of clerical sexual abuse and expressed his deep regret for their suffering. Victims' associations say the Vatican has not done enough to bring perpetrators to justice.
"The pope is doing nothing and the dioceses are trying to cover everything up," said Wilfried Fesselmann of Survivors Network of those Abused by Priests (SNAP). Victims joined 8,000 protesters on a march through Berlin at the start of the visit.
Michael Ebertz, who teaches sociology of religion in a Catholic college in Freiburg, said the pope's sermon could be a call to bishops not to let lay Catholics take over a dialogue they launched in reaction to the sexual abuse scandals.
"It could mean that, in the end, the bishops will decide what real belief is and this can't be left to the dialogue process to decide," he said on ZDF television.
In comments on Sunday afternoon, Benedict told Germans working in Catholic institutions that deeper faith was the key to overcoming the challenges facing the Church.
"It is not a question here of finding a new strategy to relaunch the Church," he said.
(Reporting by Philip Pullella and Tom Heneghan, editing by Tim Pearce)