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Pope Benedict XVI celebrated Mass for 230,000 people Tuesday in a sunny field outside Regensburg, taking his homecoming tour of his native Bavaria to the university town where he once taught theology.

Pilgrims carrying flags and folding chairs streamed into the field to cheer as Benedict rode slowly through the crowd, waving on his way to the canopied altar platform.

From atop the platform, Benedict looked over a vast, good-tempered throng dotted with blue-and-white Bavarian flags and the yellow-and-white Vatican banners.

The 79-year-old pope is making a nostalgic, six-day trip to Germany's Roman Catholic stronghold, the region where he served as archbishop of Munich from 1977 to 1982. It is his second visit to Germany since his election to succeed Pope John Paul II, after a visit to World Youth Day in Cologne in 2005.

CountryWatch: Germany

In discussing faith and reason, Benedict in his sermon scoffed at the idea of a "mathematically ordered cosmos" without any hand of God. He said this would mean "nothing more than a chance result of evolution."

"We believe in God. This is a fundamental decision on our part."

The message echoed that given during a Mass on Sunday in Munich, where Benedict warned modern societies that excessive faith in science and technology had made them "hard of hearing" and deaf to God's message.

So far on this trip, however, he has steered clear of political or social issues. He avoided commenting publicly on the fifth anniversary of the Sept. 11 terror attacks on Monday.

Many people had been out in the field all night, sleeping in cool weather under clear skies. Regional police spokesman Ludwig Steger said some 230,000 people had arrived by 9 a.m., before Benedict's arrival.

Eva Renz dozed in the sun as she waited for the pope, having been on the road since 3 a.m. with her husband and six children.

"His presence is important because he is a representative of Christ," she said. "I brought all the children because it's important for them to see this huge crowd and all the joy."

Some people turned out despite disagreeing with Benedict's conservative stands, such as his opposition to ordaining women and married men.

Machine shop worker Kurt Kellner, 40, took the day off to come, but was skeptical about whether Benedict would win him over. "I know his positions, they're not entirely my opinions. I want to take part in the event," he said, calling Benedict "relatively good" as pope.

"He knows how to move people," he said.

Werner Ott, 47, rode over on his bicycle. "I am only here out of curiosity, no other reason," he said.

He questioned what Benedict's visit would mean for the German church. "At the beginning probably more will go, then it will certainly tail off," he said.

In Regensburg, he is scheduled to address academics at Regensburg University, where he taught theology from 1969 to 1977 and served as vice president. He also plans to spend time with his brother, the Rev. Georg Ratzinger, retired choir director at the town cathedral, and visit the graves of his parents and sister. Benedict has kept his home in the city's Pentling suburb.