Returning to the city where he once taught theology, Pope Benedict XVI offered a fundamental lesson in what the church believes and why it should proclaim the faith clearly in today's anxious and violent world.

In a sermon before an estimated 300,000 people in Regensburg Sept. 12, the pope said it was necessary to recognize the modern "pathologies" associated with reason and religion and the ways that "God's image can be destroyed by hatred and fanaticism."

In light of these distortions, he said, Christians need to "state clearly the God in whom we believe and proclaim confidently that this God has a human face."

"Only this can free us from being afraid of God, which is ultimately at the root of modern atheism. Only this God saves us from being afraid of the world and from anxiety before the emptiness of life," he said.

When he arrived at the Mass site, the pope spent 20 minutes riding through the crowd in a popemobile, smiling and waving as he passed through an enthusiastic crowd. Hundreds of homemade banners expressed, in some form, the "welcome back" sentiment that prevailed in the city.

The pope was spending two days in and around Regensburg, where his older brother, Msgr. Georg Ratzinger, lives and where his parents are buried. The pope taught theology at the University of Regensburg from 1969 until his appointment as archbishop of Munich and Freising in 1977.

Speaking from beneath a hillside canopy overlooking a field on the edge of the city, the pope said he was "a bit taken aback" by all the preparation work for his visit. He offered what he called "an inadequate thank you."

On his left was situated a huge cross, which the pontiff called "a sign of God's peace in the world." The phrase underlined what has become a subtext of the pope's six-day visit and a theme of his papacy: that Christianity does not threaten people, but offers a vision based on love.

Tomas Miklos, a sugar factory worker in Regensburg, said this basic message of the German pope was resonating with younger generations. He stood with other worshippers on one of the manicured plots of grass installed for the Mass.

"I think the pope is trying to bring a new way of seeing things. Instead of war, we create love: That's the message younger people want to hear, and it's enough," he said.

"We see all these terrible images of Iraq, Israel, Beirut. And the pope is saying something about all that: Christianity is love," he said. "I think this is bringing younger people closer to the church."

In his sermon, the pope said people don't need high theology to understand the faith. "Deep down, it is quite simple," he said -- belief in God the creator, in Christ the savior and in everlasting life, as expressed in the Apostles' Creed.

He said modern attempts to make God "unnecessary" have always failed because it becomes clear that "something is missing from the equation."

"When God is subtracted, something doesn't add up for man, the world, the whole vast universe," he said, in one of several lines that drew applause from the crowd.

The pope said today's world faces two approaches to the ultimate questions about life: "What came first? Creative reason, the spirit who makes all things and gives them growth, or unreason, which, lacking any meaning ... somehow brings forth a mathematically ordered cosmos, as well as man and his reason."

He said that if seen as "nothing more than a chance result of evolution," the human becomes meaningless. Christians, on the other hand, believe that at the beginning of everything is the eternal word --- reason and not unreason, he said.

The pope completed his mini-explication of the creed by examining the church's belief in the last judgment. He said it that if the idea of judgment makes people afraid, it also brings the prospect of "the triumph of justice."

"Don't we want the outrageous injustice and suffering which we see in human history to be finally undone, so that in the end everyone will find happiness, and everything will be shown to have meaning?" he said.

Faith is not meant to instill fear but to call people to accountability, he said.

"We are not meant to waste our lives, misuse them or spend them selfishly. In the face of injustice we must not remain indifferent and thus end up as silent collaborators or outright accomplices," he said.

Not everyone who came to the Mass was an active Catholic or enthusiastic supporter of the pope. Andre Lovas, an engineer and a self-described former Catholic, said his office was closed for the papal event, so he decided to attend the liturgy instead of sitting at home.

Lovas said that although he considers the pope a "nice, smart" man he disagrees with the church on several key issues: treatment of women in the church, Catholic relations with Protestants and the church's policy against condom use.

When the pope took his popemobile tour of the crowd, he might have noticed a large Canadian flag hung on a tall platform in a corner of the Mass site. Beneath it was a smaller flag of the British Columbia city of Quesnel.

Don Gook and his wife made the trip from Quesnel to attend the papal Mass and renew ties in Regensburg, where Gook played for the city's hockey team 33 years ago.

They joined others who camped out the night before the Mass, some singing hymns to keep warm. In the morning, they watched the mist lift, revealing another glorious late-summer day for the pope's homecoming visit.

On Islamic violence

That same day, in a lecture at the German university where he once taught theology, Pope Benedict XVI used a historical critique of Islamic violence to introduce a reflection on the crisis of faith and reason in the West.

The pope began his address by highlighting a 600-year-old discussion on Islamic "jihad" or holy war, quoting at length a Christian emperor who condemned Islam for spreading the faith "by the sword."

But instead of critically assessing Islam, the pope focused his attention on what he said was the West's centuries-old tendency to "exclude the question of God" from the realm of reason.

This tendency to devalue religious thought, he said, makes it more difficult for the West to engage in the urgently needed dialogue of cultures and religions.

"A reason which is deaf to the divine and which relegates religion to the realm of subcultures is incapable of entering into the dialogue of cultures," he said.

The pope looked happy and relaxed as he returned to the University of Regensburg, where he taught dogmatic theology from 1969 to 1977. About 1,500 of Germany's leading academics greeted the pontiff with warm applause as he walked through the university's great hall and took his place on a gilded chair in the center of the stage.

To introduce the theme of his lecture, the pope quoted from an account of a dialogue between the Byzantine Emperor Manuel II Paleologus and an unnamed Muslim scholar, sometime near the end of the 14th century. The pope said the account was marginal to his theme, but that he found it interesting -- particularly when the emperor touched upon the subject of Islamic holy war.

The pope cited what the emperor told the Islamic scholar: "Show me just what Mohammed brought that was new, and there you will find things only evil and inhuman, such as his command to spread by the sword the faith he preached."

Twice, the pope emphasized that he was quoting someone else's words.

The pope said the emperor must have known of the early Islamic teaching that "there is no compulsion in religion," but was no doubt also aware of later instructions in the Koran about holy war.

In the account, the emperor goes on to explain why spreading the faith through violence is unreasonable, because violence is incompatible with God and with the nature of the soul.

The pope then pointed to a key question about Islam that is raised by the narrative: whether God is absolutely transcendent for Muslims, and therefore not bound up with "any of our categories, even that of rationality."

The pope did not offer an answer to that question. Instead, he went on to explore, in great detail, why Christian theology has come to affirm that faith is indeed based on reason and that acting unreasonably contradicts God's nature.

Asked by reporters about the papal text, Jesuit Father Federico Lombardi, the Vatican spokesman, said the pope had no intention of giving "an interpretation of Islam as violent."

"I think everyone understands that even inside Islam there are many different positions and there are many positions that are not violent," Father Lombardi said. He noted that the pope's speech was primarily a historical analysis.

The pope's main point, developed in an academic style, was that in the Western world the growing separation between faith and reason has resulted in a "dangerous state of affairs for humanity," in which society tries to construct a system of ethics without taking religion seriously and individuals try to make moral choices based solely on the subjective conscience.

He said this was partly the result of a long process of "de-Hellenization" of Christian theology, in stages marked by an overemphasis on Scripture, a reduction of the Gospel to a "humanitarian moral message" and the creation of a gulf between theology and scientific empiricism.

The pope said his broad-brush "critique of modern reason" did not aim to turn back the clock or ignore the progress made and the new possibilities opened for humanity. But the church also sees dangers, he said, and believes they can be overcome "only if reason and faith come together in a new way."

When the West invites others to a "dialogue of cultures," it should do so with the understanding that religion is an essential part of its own culture, he said. But in fact, he said, it is widely held in the Western world that the only authentic knowledge is scientific knowledge, and that religion is a purely subjective experience.

"The world's most profoundly religious cultures see this exclusion of the divine from the universality of reason as an attack on their most profound convictions," he said.

The pope said the West needs to recover the rightful place of philosophy and theology, so that it can say --- like the Byzantine emperor who debated the Muslim scholar --- that "not to act reasonably ... is contrary to the nature of God."

The Vatican underlined the academic character of the pope's address by noting on the text handed out to journalists that a later version would be issued, complete with footnotes.

---CNS