A representative of a national gay rights group who was appointed by President Obama to a White House advisory council this week once described Pope Benedict XVI and some Catholic bishops as "discredited leaders" because of their opposition to same-sex marriage.

Harry Knox, director of the religion and faith program at Human Rights Campaign, a Washington-based gay rights group, lambasted the prelates in a gay newspaper last month for their support of Proposition 8, the successful November ballot measure that made same-sex marriage unconstitutional in California.

Knox told the Bay Area Reporter that the Knights of Columbus, the Catholic fraternal service organization, were "foot soldiers of a discredited army of oppression" for their role in the campaign, saying the group "followed discredited leaders," including bishops and Pope Benedict.

"A pope who literally today said condoms don't help in control of AIDS," he said, referring to the pope's statement condemning the use of condoms in Africa.

William Donahue, president of the Catholic League, said the appointment of Knox further undermines a faith-based program that has been watered down by Obama.

"People are right to criticize the Catholic Church for anything," Donahue told FOXNews.com. "But Harry Knox is not just a critic. He's insulting. He used disdainful, disparaging terms to talk about the pope and the Catholic hierarchy. If someone were appointed using that language about homosexuals, he would be thrown out."

Donahue said he would prefer to see Obama end the faith-based initiative.

Knox did not return messages seeking comment.

Marianne Duddy-Burke, executive director of DignityUSA, an organization for gay Catholics, who has worked closely with Knox, called Knox a strong supporter of Catholicism who acknowledges the good works of the church.

"But I think he also represents a valid viewpoint in criticizing the Catholic bishops' efforts to sustain continual oppression in this country," she said, adding that they have been the primary financial backers of measures to block the human rights of gay couples. "The bishops have done a lot of damage to our communities, and [Knox's] presence in that circle brings a much needed voice."

Knox is among the 25-member advisory council that is part of the White House Office of Faith-Based and Neighborhood Partnerships.

Obama established the office in February with a broader mission than the one previously overseen by President Bush. Obama said the new office, which he created by executive order, would reach out to organizations that provide help, "no matter their religious or political beliefs."

Some have accused Obama of appointing Knox to deflect criticism from liberal groups after he invited former Indianapolis Colts coach Tony Dungy to be part of the council. Dungy, an evangelical Christian, supported efforts in Indiana to ban same-sex marriage in 2007. He declined Obama's offer, citing scheduling conflicts.

Donahue noted that Obama asked the Rev. Gene Robinson, an Episcopal bishop from New Hampshire and a vocal gay rights leader, to open his inauguration with a prayer after liberal groups decried the invitation of evangelical Pastor Rick Warren, who opposes gay marriage, to deliver the inaugural invocation.

"The counter to Dungy is Harry Knox," Donahue said. "But you don't counter a man with traditional beliefs with an anti-Catholic bigot. It's not a moral equivalent."

Duddy-Burke rejected that notion, saying Obama's selections show his respect for diversity of beliefs.

"I, as a person of faith, really applaud the president for casting a wide net in selecting a panel of religious advisers, because it represents the diversity of religious voices in the country," she said.