Pope Benedict XVI exchanges Christmas wishes with cardinals and prelates, in the Clementine Hall at the Vatican on Monday. (Max Rossi/Pool/Associated Press)

Gay groups are criticizing comments made by Pope Benedict XVI that indicated saving humanity from homosexual behaviour is more important than saving rainforests from destruction.

In a holiday address on Monday to the Curia — the Vatican's central administration — the pontiff said humanity must care for the land, water and air but also "protect humans against the destruction of himself," he said.

"A sort of ecology of man is needed," said the Pope. "The tropical forests do deserve our protection. But man, as a creature, does not deserve any less."

The Pope was trying to imply that if the entire human population were homosexual that the birthrate would be reduced to the point of extinction for humankind, said Norman Prince, president of Dignity Canada, an organization for Catholics concerned about the church's sexual theology.

"Sadly, his opinions don't seem to be based on modern understandings of human sexuality and so it amounts to more of a bullying from the pulpit," Prince said, adding that the statements were very hurtful.

The comments by the Pope were "totally irresponsible and unacceptable" and could provide some with a justification for "gay bashing," said Rev. Sharon Ferguson, the chief executive of the Lesbian and Gay Christian Movement, in an interview with the BBC.

"When you have religious leaders like that making that sort of statement, then followers feel they are justified in behaving in an aggressive and violent way," she said.

The Roman Catholic Church teaches that while homosexuality is not sinful, homosexual acts are and opposes same-sex marriage.

Earlier this month, the Vatican said that a proposed United Nations resolution decriminalizing homosexuality went too far.

"Unjust discrimination" against gay people should be avoided, but the use of wording such as "sexual orientation" and "gender identity" in the text would "create serious uncertainty in the law," the Vatican said.

In October, a Vatican official called homosexuality "a deviation, an irregularity, a wound."

Humanity needs to "listen to the language of creation" and understand the intended roles of men and women, the Pope said.

Homosexual acts are a "destruction of God's work," he said.

The Pope's comments also demonstrated "a lack of openness to the complexity of creation," Mark Dowd, a strategist with the Christian environmental group Operation Noah, told the BBC.

Some have argued the comments were meant as a denunciation of gender theory, which is the study of how sexual gender affects behaviour.

The Catholic church has repeatedly spoken out against gender theory, which many gay and transsexual groups promote as a key to understanding and tolerance.