The gay rights group Queer Kissing Flashmob staged a kiss-in protest against Pope Benedict XVI on Sunday.

About 200 gay men, lesbians and allies embraced as the Holy Father was being driven to celebrate mass at Barcelona's La Sagrada Familia (Holy Family) basilica. But the protest appeared to be drowned out by thousands of cheering, flag-waving supporters of the pontiff.

Before the protest, Carole Marylene, an organizer of the event, told Spanish news agency EFE: “It is curious to note how an act so noble as a kiss can be considered revolutionary, even in the twenty-first century.”

During the mass, Benedict attacked Spain's 2005 law legalizing gay marriage.

“The generous, indissoluble love of a man and a woman is the effective context and the foundation of human life in its gestation in the birth and growth and its natural end,” the pope said.

Last month, the pontiff had harsher words for the institution, saying gay marriage leads to confusion of society's values.

The law has become an issue in the contest to elect Spain's next prime minister in early 2012. Mariano Rajoy, the president of the country's Partido Popular, recently said he believes the law is unconstitutional, prompting gay rights activists to call him and his party “homophobic.”