Hundreds of thousands of people Sunday attended an open-air Catholic mass in Madrid designed to promote family values in a country where the Socialist government has undertaken sweeping social reforms.
Pope Benedict XVI addressed the faithful from Rome on giant screens set up in the Plaza Colon.
"Dear families, don't allow love, the opening to life and the incomparable links that unite our family to become distorted," the pope said in his Sunday Angelus prayer.
The Archbishop of Madrid, Antonio Maria Rouco Varela, issued an appeal against "the shocking cruelty" of abortion, calling on families to overcome the "culture of death."
Spain's Socialist government has said it plans to introduce a new law that would offer greater legal protection for women who wish to have an abortion and doctors who carry out the procedure.
Since first coming to office in 2004, the government of Prime Minister Jose Luis Rodriguez Zapatero has moved to transform Spanish society with a series of liberal social reforms, including same-sex marriages and fast-track divorce, which have enraged the Roman Catholic Church.
The bishop of Bilbao, Ricardo Blazquez, Sunday condemned any move "to call marriage the union of two people of the same sex" when a "normal family" is made up of "a stable union... between a man and a woman."
A huge Catholic mass in Madrid a year ago provoked tensions between the Church and the government after bishops criticised Zapatero's social policies, less than three months before general elections in which the Socialists were re-elected.