Several hundred thousand people massed at the Eiffel Tower in Paris on Sunday to protest against President Francois Hollande's plan to legalize gay marriage and adoption by June.
Three columns of protesters, waving pink and blue flags showing a father, mother and two children, converged on the landmark from different meeting points in Paris. Many came after long train and bus rides from the provinces.
Hollande has pledged to push through the law with his Socialists' parliamentary majority but the opponents' campaign has dented public support and forced deputies to put off a plan to allow lesbian couples access to artificial insemination.
Champ de Mars park at the Eiffel Tower was packed, but turnout estimates varied widely. Organisers claimed 800,000 had protested, while police put the number at 340,000, high even in protest-prone France.
"Nobody expected this two or three months ago," said Frigide Barjot, a flamboyant comedian leading the "Demo for All". At the rally, she read out a letter to Hollande asking him to withdraw the draft bill and hold an extended public debate on the issue.
Strongly backed by the Catholic Church hierarchy, Barjot and groups working with her mobilized church-going families and political conservatives as well as some Muslims, evangelicals and even homosexuals opposed to gay marriage to protest.
Hollande's office said the turnout was "substantial" but would not change his determination to pass the reform.
TOLERANT BUT CONCERNED
"The French are tolerant, but they are deeply attached to the family and the defense of children," said Daniel Liechti, vice-president of the National Council of French Evangelicals, which urged its members to join the march.
Opponents of gay marriage and adoption, including most faith leaders in France, have argued that the reform would create psychological and social problems for children, which they believe should trump the desire for equal rights for gay adults.
Hollande has angered those opposed to same-sex marriage by trying to avoid public debate on the reform, which Justice Minister Christiane Taubira described as "a change of civilization", and then wavering about some of its details.
His clumsy handling of other promises, such as a 75 percent tax on the rich that was ruled unconstitutional, and a faltering struggle against rising unemployment have dented his popularity in recent opinion polls.
CATHOLIC PROTESTS IN BRITAIN, ITALY
Same-sex weddings are legal in 11 countries including Belgium, Portugal, the Netherlands, Spain, Sweden, Norway and South Africa, as well as nine U.S. states and Washington D.C.
Over 1,000 Catholic clerics in Britain issued a protest letter on Saturday against plans to legalize gay marriage there.
In Italy, the Vatican daily L'Osservatore Romano on Sunday condemned a court ruling against a father who sought custody of his son because the mother now lives with her female partner.
The marches in near-freezing temperatures included young and old protesters, many of them couples with children in tow, in strollers or on their fathers' shoulders.
"I am perfectly happy that homosexual couples have rights and are recognized from a civil point of view," said protester Vianney Gremmel. "But I have questions regarding adoption."
Cardinal Andre Vingt-Trois, a Catholic leader who launched the opposition with a critical sermon in August, greeted protesters in southern Paris but did not march with them.
Support for gay marriage in France has slipped by about 10 percentage points to under 55 percent since opponents began speaking out, according to surveys, and fewer than half of those polled recently wanted gays to win adoption rights.
Under this pressure, legislators dropped a plan to also allow lesbians access to artificial insemination.
Organisers insist they are not against gays and lesbians but for the rights of children to have a father and mother.
Slogans on the posters and banners approved by the organisers included "marriagophile, not homophobe," "all born of a father and mother" and "paternity, maternity, equality."
Civitas, a far-right Catholic group that sees homosexuality as a sin, staged a much smaller march along another route.
(Editing by Will Waterman)