Pope Benedict XVI warned Sunday that modern culture is pushing God out of people's lives, causing nations once rich in religious faith to lose their identities.

Benedict celebrated a Mass in the Basilica of St. Paul Outside the Walls to open a worldwide meeting of bishops on the relevance of the Bible for contemporary Catholics.

"Today, nations once rich in faith and vocations are losing their own identity, under the harmful and destructive influence of a certain modern culture," said Benedict, who has been pushing for religion to be given more room in society.

The meeting of 253 bishops, known as a synod of bishops, will run from Monday through Oct. 26. The Vatican said that despite Benedict's efforts to improve relations with Communist China, no bishops have come from the mainland, although there are prelates from Macau and Hong Kong.

"Surely they tried, I mean the Holy See tried but obviously they could not make agreement," Hong Kong Cardinal Joseph Zen told AP Television News as he entered the basilica.

"Maybe the Holy See welcomes someone that they (the Chinese) would not allow," he said, adding that China might try to send a bishop who is not acceptable to the Holy See.

Chinese bishops have not been allowed to travel to similar meetings in the past.

Ties between the Vatican and China's communist government have long been strained. Beijing objects to the Vatican's tradition of having the pope name his own bishops, calling it interference in China.

China appoints bishops for the state-sanctioned Catholic church. In recent years, some of those bishops have received the Vatican's tacit approval.

Still, many of the country's estimated 12 million Catholics worship in congregations outside the state-approved church with bishops loyal to the pope.

A document prepared for the meeting rejects a fundamentalist approach to the Bible and said a key challenge was to clarify for the faithful the relationship of scripture to science. A rabbi will address the conference on Monday in what is believed to be the first time a Jew has participated in such a meeting.