The Roman Catholic Church in Argentina is rallying its faithful to demonstrate before Congress against a gay marriage bill as senators prepare to consider the legislation, the AFA reported.

The Senate is expected to vote Wednesday on a gay marriage bill approved in May by the country's lower house, the Chamber of Deputies (la Camara de Diputados). The Senate General Law committee, however, has recommended the Senate take up a bill that recognizes gay couples with civil unions but does not allow for adoption, and reject the marriage bill.

In calling on Catholics to attend Tuesday's protest, Buenos Aires Archbishop Jorge Bergoglio warned that the legalization of gay marriage is being driven by the devil.

“Let's not be naïve, we're not talking about a simple political battle; it is a destructive pretension against the plan of God,” Cardinal Jorge Bergoglio wrote in a letter calling on followers to join an anti-gay marriage rally in the nation's capital.

“We are not talking about a mere bill, but rather a move by the Father of Lies which aims to confuse and deceive the children of God.”

President Cristina Fernandez de Kirchner, who supports the legislation, said the church's tone was reminiscent of “medieval times and the Inquisition.”

“It is disturbing to hear phrases like war of God or the devil's projects, which are things that take us back to medieval times and the Inquisition,” Kirchner told the Argentine press during an official visit to China.

Ninety-one percent of Argentinians say they are members of the Catholic Church.

The church is promoting the demonstration with the theme “We want a mommy and a daddy.” A reference to the fact that the bill would allow married gay couples to adopt children.

The measure enters the final round of voting with a sight lead, 32 senators in favor and 30 against. But 10 senators remain undecided and many have said they'll back the civil unions bill.

The president of the National Institute against Discrimination, Xenophobia and Racism (INADI), Claudio Morgado, said the civil unions bill “has the same construct as apartheid” and if approved would discriminate against gay couples who would be given an inferior legal status to heterosexual couples.

If approved, Argentina would become the first Latin American country to legalize gay marriage. The institution is also legal in Mexico City, but the federal government is challenging the law in court.