PARIS (Reuters) - France's governing Socialist Party hit back hard at the Roman Catholic Church on Sunday for campaigning against its plan to legalise same-sex marriage, heralding a bruising debate over the issue.
Paris Cardinal Andre Vingt-Trois spoke against the proposed law on Saturday and encouraged Catholics to write to their elected officials and take to the streets in protest against the reform due to be voted on by mid-2013.
Opinion polls show that backing for the plan, a campaign promise by President Francois Hollande, has slipped several points since leaders of France's main religions began speaking out against it and now stands at just under 60 percent.
The government is due to present the draft text of the law to the cabinet on Wednesday.
"I'm shocked by this attitude which I think is a kind of return to a fundamentalism that I find problematic," Jean-Marie Le Guen, Socialist senator from Paris, said of Vingt-Trois's speech to bishops in the pilgrimage town of Lourdes.
Party spokesman David Assouline said it was not the Church's role "to oppose the will of the legislature, especially concerning civil marriage in a secular republic."
In his Lourdes speech, Vingt-Trois, who is head of the bishops' conference, said legalising same-sex marriage would profoundly affect the equilibrium of French society and harm children who would grow up without a father and a mother.
"It will not be 'marriage for all'," he said, citing the slogan of campaign for gay matrimony, "it will be the marriage of a few imposed on all".
If the law passes, France - a traditionally Catholic society where churchgoers are now a single-digit minority - would become the 12th country in the world to allow same-sex marriage.
Erwann Binet, the Socialist Party's expert on the issue, said he hoped "the Catholics don't try to impose their vision of the family on the society."
He told the Le Parisien newspaper France now had many different types of families, including homosexuals who are bringing up children. "We parliamentarians should assure that all these forms of family can have the same rights," he said.
He also said that gay couples should have the right to adopt children or to resort to medically assisted procreation, both of which are only allowed to heterosexuals now.
The Catholic Church and France's Jewish, Muslim, Orthodox Christian and Buddhist religious minorities have been especially severe in criticising the provisions for gay adoption and assisted procreation.
Some Socialist deputies have expressed doubts about including these provisions in the law to legalise gay marriage and it was not clear if the draft text would include them.
Lay Catholic groups organised protests in 75 cities around France last month and plan more in mid-November. Although he encouraged Catholics to join in, Vingt-Trois said it was not his role to lead a street protest.
Some conservative politicians have spoken out in favour of a large street protest in Paris and some mayors, the main officials who celebrate civil marriages, have said they would not preside over ceremonies for gay couples.
Laurent Wasquiez, a leading deputy in the conservative opposition UMP party, defended Vingt-Trois's open criticism of the plan and called on the government to take more time to seek a consensus about any change in the definition of marriage.
"The government wants to rush this through, without taking the time to get everyone around the table," he told France 3 television.
France legalised gender-neutral civil unions in 1999 and almost as many are now contracted every year as traditional marriages. But only four percent of those are among same-sex couples.
Reporting By Tom Heneghan; Editing by Stephen Powell