Thanking the crowd for their presence and affection, Pope Benedict said, “The true enemy to fear is sin, the spiritual evil that unfortunately sometimes infects even members of the Church.”

“We Christians are not afraid of the world . . . Rather we must fear sin and, for that reason, be strongly rooted in God,” he said, adding that the Church can become holier by going through “the trials” it is facing.

He also prayed that abuse victims would return to participating in the life of a “purified” Church, so that they could “rediscover the infinite love of Christ.”

In a rare exception, Vatican officials allowed the organizers to hang banners from the colonnade surrounding the square. Many proclaimed, “Together with the Pope.”

Dozens of other signs, banners, balloons and flags expressed love for the Pope, with words such as, “We young people are with you” and “The people of Rome with the Pope.”

At his last stop in a four-day trip to Portugal, the Pope received the kind of welcome that buoyed his spirits throughout the visit. Residents of the northern city of Porto — about 150,000 of them — turned out to cheer, wave, sing and pray May 14 as the Pope arrived to celebrate Mass in a central city square.

The 83-year-old Pope, who has looked a bit beleaguered at the Vatican recently, wore a broad smile as he waved to a multitude that stretched several city blocks. People crowded the balconies and windows of office buildings, which were decorated with three-storey-tall flower garlands. Down at street level, the enthusiasm was palpable.

Young people wore Pope T-shirts, families held home-made posters and everyone seemed to have flags that read: Bem-vindo Papa Bento (Welcome Pope Benedict).

Secularism might have made inroads in Portuguese society, but that didn’t dampen the excitement and happiness as many stood for hours in a light rain to attend the papal liturgy.

“We love the Pope, who he is and what he represents,” said Elisabete Borges in Porto.

Pope Benedict also referred to the sex-abuse scandal when he wrote to participants in a large ecumenical gathering in Germany. The Pope said that at a time when the world’s people are in need of hope, some people are asking if the Church really is a place to find it.

“In the past few months, we repeatedly have had to face news that could attempt to remove the joy from the Church, news that obscures it as a place of hope,” he said.

“Weeds exist even in the heart of the Church . . . but the good grain has not been suffocated by the seed of evil,” the Pope said.