VATICAN CITY — Pope Benedict XVI travels to Spain this weekend as part of his campaign to defend the traditional family, visiting a predominantly Roman Catholic country that allows gay marriage, divorce and abortion.

Hundreds of thousands of pilgrims are expected when Benedict arrives to address an international meeting on the family that was organized by the Vatican in the city of Valencia on Spain's Mediterranean coast.

For months, Benedict has been denouncing gay marriage and other challenges to church doctrine in Europe and elsewhere — recently summed up by the Vatican as the "greatest threat ever" to the traditional family based on marriage between a man and a woman.

But the location of the meeting in Spain has particular significance because of the church's battle with the Socialist government, which took office two years ago with an agenda that included legalizing gay marriage, streamlining procedures for abortion and divorce, and scrapping plans by the previous conservative government to make religion classes obligatory in schools.

Relations have been so strained between the Holy See and Madrid that a meeting between Benedict and Spanish Prime Minister Jose Luis Rodriguez Zapatero was confirmed only a few weeks before the trip. The meeting is scheduled to take place in Valencia today on Benedict's turf — the residence of Valencia's archbishop.

"I don't believe there will be a clash," Bishop Ricardo Blazquez Perez, president of the Spanish bishops' conference, told the Italian religious affairs magazine Famiglia Cristiana. "The church will say what it thinks, and Zapatero will hear directly from the pope about what the Spanish parliament has approved."

Zapatero will greet the pope at the airport and meet with him today, a spokeswoman for Spain's government told The Associated Press on Thursday. But the premier will not go to the Mass that Benedict is scheduled to celebrate tomorrow.

The Mass will be attended by Foreign Minister Miguel Angel Moratinos, and Benedict also is set to meet Deputy Prime Minister Maria Teresa Fernandez de la Vega, who is from Valencia.

"This is a world meeting, but you can be sure Benedict will deal with the Spanish issues in his usual restrained and measured way," the Rev. Giovanni Marchesi, an Italian Jesuit who follows family issues, told The Associated Press.

Benedict, a German, has made combating a Europe of empty churches and religious apathy a priority of his papacy. Vatican officials have declared that such former Catholic bedrocks as Spain are in need of what they call a "new evangelization."

In recent years, the Netherlands, Belgium and Canada as well as Spain have legalized same-sex marriage, while Britain and several other European countries now give such couples the right to form partnerships that entitle them to most of the same tax and pension rights as married couples.

The 79-year-old pope is making his third foreign trip since assuming the papacy in April 2005. All have been within Europe, with a pilgrimage to his native Germany scheduled in September.

Surveys have shown that Spain has rapidly joined the secular path of other Western European countries following the fall of Gen. Francisco Franco's 1939-1975 dictatorship, under which the church enjoyed special privileges.

In May, upon receiving Spain's new ambassador to the Holy See, Benedict made his agenda quite clear.

"The church proclaims without reserve the primordial right to life, from conception to natural death, the right to ... live in a family without it being substituted or confused by other forms or different institutions," Benedict said.

The Valencia meeting is organized by Cardinal Alfonso Lopez Trujillo, head of the Pontifical Council for the Family, who recently expressed worry that the Vatican's opposition positions could one day land it before an international court of justice.

"We worry especially that, with current laws, speaking in defense of life and the rights of families is becoming in some societies sort of a crime against the state," he said.

Lopez Trujillo, a Colombian, made headlines in 2003 when he said condoms did not prevent AIDS and may help spread it by creating a false sense of security.