Pope Benedict was accused of stoking homophobia today after a speech in which he declared that saving humanity from homosexuality was just as important as saving the rainforest from destruction.

The Pontiff made the remarks yesterday in an end-of-year address to the Curia, the Vatican's central administration. He said that humanity needed to listen to the "language of creation" to understand the intended roles of man and woman and behaviour beyond traditional heterosexual relations was a "destruction of God’s work".

"The tropical forests do deserve our protection. But man, as a creature, does not deserve any less," he told scores of prelates gathered in the Vatican's Clementine Hall.

"What’s needed is something like a ‘human ecology,’ understood in the right sense. It’s not simply an outdated metaphysics if the Church speaks of the nature of the human person as man and woman, and asks that this order of creation be respected."

It is not the first time that the Pope has used the Curia speech to throw out a controversial idea – two years ago he complained that Islam had yet to learn the lessons of the Enlightenment – but the comments were quickly denounced by gay and lesbian groups, both inside and outside the Church.

The Rev Sharon Ferguson, chief executive of the Lesbian and Gay Christian Movement, described the Pope's comments as "totally irresponsible and unacceptable in any shape or form". She said: "It is more the case that we need to be saved from his comments. It is comments like that that justify homophobic bullying that goes on in schools and it is comments like that that justify gay-bashing.

"There are still so many instances of people being killed around the world, including in Western society, purely and simply because of their sexual orientation or their gender identity.

"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 because they feel that they are doing God’s work in ridding the world of these people."

Her views were echoed by the Reverend Dr Giles Fraser, the vicar of Putney and president of Inclusive Church, the pro-gay Anglican movement. "I thought the Christmas angels said ’Fear not’. Instead, the Pope is spreading fear that gay people somehow threaten the planet. And that’s just absurd ... Can’t he think of something better to say at Christmas?"

Pam Spaulding, a leading lesbian blogger from the United States, was even more direct. She said: "The Prada Papa Ratzi opens his trap again, and the homophobia stinks like trash piled up during a NYC garbage strike."

The Catholic Church teaches that while homosexuality is not sinful, homosexual acts are. It opposes gay marriage and, in October, a leading Vatican official called homosexuality "a deviation, an irregularity, a wound".

The Pope's speech was also seen, however, as a denunciation of "gender theory" – the study of how gender assignments affects the behaviour of individuals. The Catholic Church has repeatedly spoken out against gender theory, which gay and transsexual groups promote as a key to understanding and tolerance.

"That which is often expressed and understood by the term ‘gender’ in the end amounts to the self-emancipation of the human person from creation and from the Creator," the Pope said.

"Human beings want to do everything by themselves, and to control exclusively everything that regards them. But in this way, the human person lives against the truth, against the Creator Spirit."

Mark Dowd, campaign strategist at Operation Noah, the Christian environmental group, who is a gay man and a former Dominican friar, said that the Pope’s remarks were "understandable but misguided and unfortunate".

He said that he understood the Pope’s vision of creation in which rainforests were protected and men and women "complement one another, reproduce and live happily ever after".

But he said: "The problem is that if you study ecology seriously as any intelligent man would do, and the Pope is a fantastically intelligent man, you realise that ecology is complex, it has all sort of weird interdependencies and it is the same with human sexuality.

"It is not a one-size-fits-all model, there are lots of differences, so therefore I think it is really sad that these comments betray a lack of openess to the complexity of creation."