FREIBURG, Germany (AP) — Pope Benedict XVI celebrated the third and final Mass of his visit to his native Germany on Sunday, making a strong appeal for unity among Catholics and with the Vatican.

Some 100,000 faithful filled an airfield beside Freiburg's airport under a crystal clear blue autumn sky. It was the largest turnout of the pontiff's four-day trip, police and the local diocese said.

Benedict strongly urged the pilgrims to let their lives be guided by their faith, saying even those who doubt God's existence "are closer to the kingdom of God than believers whose faith is routine and who regard the church merely as an institution, without letting their hearts be touched by faith."

The pope's remarks to his German flock are "an encouragement to follow the path of faith in today's society," said the head of the country's Bishops Conference, Archbishop Robert Zollitsch.

But the pope is visiting a Germany where church teaching on such issues as priestly celibacy, contraception, homosexuality and a ban on women becoming priests are heavily contested, while a clerical sex abuse scandal is one of the reasons cited for the departure of tens of thousands of Catholics from the German church.

"The church in Germany will continue to be a blessing for the entire Catholic world if she remains faithfully united with the successors of St. Peter and the Apostles," Benedict said in a homily urging German Catholics to "work together in unity."

"Dear friends, in the last analysis, the renewal of the church will only come about through openness to conversion and through renewed faith," he said from an altar set up on a small hill.

But not all faithful were convinced.

"The pope spoke about humility and responsibility. But he failed to mention the church's own responsibility regarding the issue of sexual abuse cases," said Stefan Haak.

"The church, too, is fallible," said the 46-year-old from Freiburg, who had brought his two children to attend the Mass.

The pope has drawn large crowds at his stops in Berlin and in mainly Protestant eastern Germany, but the numbers were largest in this heavily Catholic southwestern city.

There have also been scattered protests, the largest drawing thousands in Berlin.

Benedict alluded to the dissent in Catholic ranks on Saturday night, when he said that through the years "damage to the church comes not from opponents, but from uncommitted Christians."

Many in Sunday's crowd waved yellow and white Vatican flags beneath a bright blue sky as they waited for the Mass to begin.

"It is beautiful to realize that one is not alone. It gives you a feeling of greater community," said Thamah Huyen Nguyen, a 26-year-old pilgrim from Freiburg.

Julia Eibeck, from Stuttgart, appeared moved by the pope's homily.

"He made it clear that the church must be lively, that it's not about the organization but about what one has in his heart," Eibeck said.

Others said experiencing a Mass led by the pope combined with the feeling of community was a unique experience for them.

"It's all about a joint experience, you see how many people turn out to pray with the pope, that creates a dynamic of its own," said Joachim Zimmermann, 51, from Freiburg.

The 84-year-old pope has seemed tired at times during the four-day-visit, but his spokesman said "he's extraordinarily well" despite the heavy schedule.

"We are surprised that he managed so well this trip that was so intense. It's a great satisfaction for us," Federico Lombardi said.

The pope was scheduled to return to Rome later Sunday.