BERLIN (Reuters) - Germans opposed to Pope Benedict's conservative views on sexuality and angry at cases of abuse by priests protested in Berlin on Thursday at the start of his four-day visit to his homeland, where record numbers have quit the Catholic Church.
The German-born pope said before landing he understood why some were "scandalised by these crimes" and had left the Church.
He used a biblical image of Jesus the fisherman to say: "The Church is a net of the Lord that pulls in good fish and bad fish."
But the 84-year-old pope's words at the start of his third and toughest papal tour of Germany failed to soothe protesters gathering in Berlin ahead of his speech to the Bundestag lower house of parliament, and mass for 70,000 at the Olympic Stadium.
"This is impossibly arrogant, it shows he is not of this world," said 62-year-old Birk Friedrich, who spent the first 14 years of his life in a Catholic children's home where he said violent abuse was rife.
"It was the Church and this pope who allowed all of the abuse to be swept under the carpet," said Friedrich in Berlin's Potsdamer Platz, where the banners included one reading "Better God without a Church than a Church without God."
Gay and lesbian groups opposed to Benedict's dogmatic views on sexuality and contraception thronged the square, some dressed as bishops or even the pope.
"Why has he been invited to parliament? He has nothing to do with politics. His policies on condoms are as good as murder," said Markus Schuke, a 42-year-old working for and AIDs charity.
In a country rocked by the clerical sex scandals sweeping across Europe in the past two years, a record 181,000 people quit the Church last year -- for the first time more than the number of Protestants leaving their churches and of baptisms into the Catholic Church.
Benedict noted this exodus and urged Catholics not to quit the Church as it worked to undo the harm done.
The Church in Germany has received almost 600 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.
About 100 left-wing deputies from the 620-member Bundestag planned to boycott the pope's speech, saying it violates the separation of church and state.
"The pope can celebrate mass wherever he wants -- in a field, a church or the Olympic Stadium. But he should not speak in the Bundestag," said Hans-Christian Stroebele of the Greens.
The pope told reporters on the plane he was not concerned about the protests, saying: "It is part of our freedom and we must acknowledge that secularism and opposition to Catholicism in our societies is strong."
German President Christian Wulff -- a Catholic who has divorced and remarried in defiance of Church dogma on the sanctity of marriage -- hinted at his own situation in his welcoming speech speaking about the Church's new challenges.
"How mercifully does it deal with failures in people's private lives?" he asked the Bavarian-born pontiff.
Wulff asked about the Church's "failures in its own history and in the misconduct of its officials" in a clear reference to the abuse scandals that have cast a shadow over his papacy.
Benedict is expected to meet abuse victims at some point during this trip, as he has done in other countries, as well as holding talks with Jewish and Muslim community leaders.
Both Wulff and Benedict noted that religion's role was shrinking in Germany, where about one third of the population is Catholic, one third Protestant and one third unaffiliated or belonging to a minority faith like Judaism or Islam.
"You have come to a country where the Christian faith can no longer be taken for granted," Wulff told the pontiff.
The pope's two previous visits home since his 2005 election were to the mostly Catholic regions of the Rhineland and his native Bavaria. This trip takes him to the mostly Protestant and atheist eastern part of Germany.
Merkel, daughter of a Lutheran minister, said she and the pope discussed the euro zone crisis: "We spoke about financial markets and the fact that politicians should have the strength to work constructively for the people and not be pushed around."
Benedict's spokesman Federico Lombardi said he had "praised Germany's contribution to resolving the crisis" to Merkel.
On Friday, Benedict will travel to the eastern city of Erfurt to meet Protestant leaders in the monastery that once housed the 16th century reformer Martin Luther, whose teachings led to Europe's split between Catholics and Protestants.
Germany's Protestants hope Benedict will consider joint communion services and let Protestant spouses of Catholics receive the Eucharist at Catholic mass. The Vatican rejects this, saying Catholics and Protestants understand the rite differently.
After Erfurt, Benedict will visit Etzelsbach, where a small Catholic community withstood persecution under East Germany's officially atheist communist rule. He will end his German tour in the mostly Catholic southwestern city of Freiburg.
Writing by Tom Heneghan and Stephen Brown; Additional reporting by Alex Hudson; Editing by Peter Graff and Elizabeth Piper