Tens of thousands of demonstrators assembled in front of the French senate building in Paris Sunday to protest a bill that would extend the use of in vitro fertilization to unmarried women and lesbians.

According to French media, the central bone of contention with the bill, which already passed the National Assembly and will soon be considered by the Senate, is that it intentionally deprives children of a father, sending a message that fatherhood is dispensable.

Many of the demonstrators carried banners emblazoned with the words “Liberté, égalité, paternité” (liberty, equality, fatherhood), a riff on the slogan of the French Revolution, Liberté, égalité, fraternité.

More than 20 different pro-family organizations, many of them Catholic, sent representatives to the protest, where members of the clergy were also visible.

“It is a question of the conception of the human person,” said one local priest from the outskirts of Paris, Father Frédéric Desquilbet. “Our society will pay very dearly for this unbalancing of the family.”

The French bishops have encouraged the faithful to protest the new bill, lending their voices to those who see the proposal as a serious disruption of the institution of the family and an assault on children.

The president of the French Bishops’ Conference, Reims archbishop Eric de Moulins-Beaufort, said that French legislators are “blind” to the long-term effects of their decision, while Rennes archbishop Pierre d’Ornellas, an expert in bioethics, said that the new bill constitutes a “revolution of the law of parentage” unwanted by the French people.

“We are in the era of Professor Nimbus and the mad scientists,” added Paris archbishop Michel Aupetit.

In her address at the rally, former legislator Marion Maréchal said the French government is seeking “to voluntarily deprive a child of a father or to transform him and the mother who carries him into a consumer product.”

Prior to the new bill’s adoption, French law limited IVF to married couples and those who have cohabited for at least two years.

Follow @tdwilliamsrome