VATICAN CITY - Iraqi Christians celebrated a somber Christmas in a Baghdad cathedral stained with dried blood, while Pope Benedict XVI exhorted Chinese Catholics to stay loyal despite restrictions on them in a holiday address laced with worry for the world's Christian minorities.

Saturday's grim news seemed to highlight the pope's concern for his flock's welfare.

In northern Nigeria, attacks on two churches by Muslim sect members claimed six lives, while bombings in central Nigeria, a region plagued by Christian-Muslim violence, killed 32 people, officials said.

Eleven people including a priest were injured by a bombing during Christmas Mass in a police chapel in the Philippines, which has the largest Catholic population in Asia. The attack took place on Jolo island, a stronghold of al-Qaida linked militants.

But joy seemed to prevail in Bethlehem, the West Bank town where Jesus was born, which bustled with its biggest crowd of Christian pilgrims in years.

The suffering of Christians around the world framed much of the pontiff's traditional Christmas Day "Urbi et Orbi" message (Latin for "to the city and to the world"). Bundled up in an ermine-trimmed crimson cape against a chilly rain, he delivered his assessment of world suffering from the central balcony of St. Peter's Basilica.

Benedict's exhortation to Catholics who have risked persecution in China highlighted a spike in tensions between Beijing and the Vatican over the Chinese government's defiance of the pope's authority to name bishops. The pope has also been distressed by Chinese harassment of Rome-loyal bishops who didn't want to promote the state-backed official Catholic church.

"May the birth of the savior strengthen the spirit of faith, patience and courage of the faithful of the church in mainland China, that they may not lose heart through the limitations imposed on their freedom of religion and conscience," Benedict said, praying aloud.

Chinese church officials did not immediately comment late Saturday. A day earlier, one said the Vatican bears responsibility for restoring dialogue after it had criticized leadership changes in China's official church.

Persecution of Christians has been a pressing concern at the Vatican of late, especially over its dwindling flock in the Middle East. Christians only make up about 2 percent of the population in the Holy Land today, compared to about 15 percent in 1950. Earlier this month Benedict denounced lack of freedom of worship as a threat to world peace.

In Iraq, Christians have faced repeated violence by militants intent on driving them out of the country.

At Our Lady of Salvation church in Baghdad, bits of dried flesh and blood remained stuck on the ceiling, grim reminders of the Oct. 31 attack during Mass that killed 68 people. Black cassocks representing the two priests who perished in the al-Qaida assault hung from a wall. Bullet holes pocked the walls of the church, now surrounded by concrete blast barriers.

Reflecting the pope's hope that Christian minorities can survive in their homelands, Archbishop Matti Shaba Matouka told the 300 worshippers: "No matter how hard the storm blows, love will save us."

After the October siege, about 1,000 Christian families fled to the relative safety of northern Iraq, according to U.N. estimates.

More than 100,000 pilgrims poured into Bethlehem since Christmas Eve, twice as many as last year, Israeli military officials said, calling it the highest number of holiday visitors in a decade.

"(It's) a really inspiring thing to be in the birthplace of Jesus at Christmas," said Greg Reihardt, 49, from Loveland, Colorado.

Still, visitors entering Bethlehem had to cross through a massive metal gate in the separation barrier that Israel built between Jerusalem and the town during a wave of Palestinian attacks in last decade.

Benedict said he hoped Israelis and Palestinians would be inspired to "strive for a just and peaceful coexistence."

The pope also prayed that Christmas might promote reconciliation in the tense Korean peninsula.

The top U.S. and NATO commander in Afghanistan crisscrossed the country, making a Christmas visit to coalition troops at some of the main battle fronts in a show of appreciation and support in the 10th year of the war against the Taliban.

Gen. David Petraeus started his visit by traveling in a C-130 cargo plane from the capital, Kabul, to the northern province of Kunduz, telling troops with the U.S. Army's 1-87, 10th Mountain Division that on this day, there was "no place that (he) would rather be than here" where the "focus of our effort" was.

Snow in Europe and the United States kept many from reaching their loved ones in time for the holidays. At airports in Paris and Brussels, hundreds of travelers received their own special Christmas present - a flight out after spending Christmas Eve curled up on hard terminal floors.

"I've never had such a Christmas before," said Ron Van Kooe, who slept overnight at the Brussels terminal. "It's one not to forget."

A rare white Christmas in the southern U.S. was complicating life for travelers as airlines canceled some 500 flights Saturday, including 300 of the 800 scheduled departures from Atlanta's international airport.

"They canceled hundreds of flights and there hasn't even been a drop of rain," said Stephanie Palmer. "This doesn't make sense."

Brian Korty of the National Weather Service said travelers in the northern Mid-Atlantic region and northeastern New England states may want to rethink Sunday travel plans due to a storm that could dump 5 inches (12.5 centimeters) or more of snow on the Washington area.

"They may see nearly impossible conditions to travel in," Korty said.