Pope Benedict XVI addressed Germany's parliament in the historic Reichstag building Thursday, warning that politicians must not sacrifice ethics for power and evoking the Nazi excesses of his homeland as a lesson in history.
Amid scattered protests outside and a boycott by some lawmakers, Benedict began his first state visit to Germany in a bid to stem the tide of Catholics leaving the church while acknowledging the damage caused by the clerical sex abuse scandal.
The pope spoke for 20 minutes in the Reichstag, which was torched in 1933 in an incident used by Adolf Hitler to strengthen his grip on power.
"We Germans know from our own experience" what happens when power is corrupted, Benedict said, describing Nazis as a "highly organized band of robbers, capable of threatening the whole world and driving it to the edge of the abyss."
But he said that even under the Nazi dictatorship, resistance movements stuck to their beliefs at a great risk, "thereby doing a great service to justice and to humanity as a whole."
He also urged all Germans not to ignore religion.
"Even today, there is ultimately nothing else we could wish for but a listening heart -- the capacity to discern between good and evil, and thus to establish true law, to serve justice and peace," he said.
Benedict also voiced strong support for Germany's ecological movement, calling it "a cry for fresh air which must not be ignored or pushed aside."
After the speech, he met with a 15-member Jewish delegation, noting that it was in Berlin that the annihilation of European Jews was organized.
"The supposedly 'almighty' Adolf Hitler was a pagan idol, who wanted to take the place of the biblical God," Benedict said according to a prepared text.
The Bavarian-born pontiff was met on a red carpet at Berlin's Tegel airport by German Chancellor Angela Merkel and President Christian Wulff at the start of his four-day visit.
Flagging Christian influence in Europe was one of Benedict's key themes.
"We are witnessing a growing indifference to religion in society," he said at a formal welcoming ceremony at the German president's Bellevue palace. He called religion a foundation for a successful society and said its values were essential for freedom.
Over the next four days, the pope has meetings with leaders of Germany's Jewish and Muslim communities, three Masses and an ecumenical service with Lutheran church members.
During his trip, Benedict was not expected to meet with Catholic dissidents who have called for allowing women priests and ending mandatory celibacy for priests.
He told reporters on the plane that the church needs to examine why people have been leaving recently and the part that the cleric abuse scandals have played in that.
"I can understand that some people have been scandalized by the crimes that have been revealed in recent times," he said. "[There are both] good and bad fish in the Lord's net."