The Catholic Church has lashed out at Mexico City lawmakers who approved a gay marriage bill widely expected to become law.

City legislators led by the leftist Democratic Revolution Party (Partido de la Revolution Democratica, PRD) overwhelmingly approved the bill on a 39 to 20 vote that included five abstentions. Mexico City Mayor Marcelo Ebrard is expected to sign the bill into law. The bill only effects Mexico's capital, one of the world's largest cities with nearly 9 million residents.

After the December 21 vote, members of the conservative National Action Party (Partido Accion Nacional, PAN) decried the action, saying giving gay couples the right to adopt was going too far and vowed to appeal to the country's Supreme Court.

Through a spokesman, Cardinal Norberto Rivera Carrera, the archbishop of Mexico, called the PRD politicians who approved the bill “dangerous.”

“In society there is no doubt: the PRD is a danger to the family,” Father Hugo Valdemar said in an interview posted on the archbishop's website.

Invoking the name of the Holy Father, he also called on voters to oust PRD members who “undermine our faith.”

“The Pope has said repeatedly: In conscience, a Catholic cannot vote for candidates or parties that promote the destruction of fundamental values and undermine our faith.”

And he called giving gay couples the right to adopt a “grave injustice.”

“Who is worried about the rights of children to have a father and a mother? Who's worried about the discrimination suffered by not having a heterosexual couple as parents?” he asked.