The Pope has declared that saving the world from homosexual behaviour is as important as saving the rainforests.
In a Christmas message, Benedict XVI stressed the importance of traditional marriage and condemned gay acts as against God's will.
He also attacked transsexuals, saying: 'It is not man who decides who is a man or woman but God.'
Christmas message: Pope Benedict says saving humanity from gays is as important as saving the rainforest from destruction
Pope Benedict, 82, known as God's Rottweiler for his hardline views, made the comments in his festive address to the Vatican's governing body, the Curia.
He said: 'The Church must defend not only the earth, the water and the air as gifts of creation belonging to everyone, but it must also protect mankind against the destruction of itself.
'The tropical forests deserve our protection, but man as a creature deserves it no less.'
In a clear reference to homosexuality, he said the failure to respect the union between a man and a woman amounted to the 'auto destruction of mankind'.
Humanity needed to 'listen to the language of creation' to understand the intended roles of man and woman, he added. Anything that deviated from this was a 'destruction of God's works'.
The Pope – who acquired a reputation as an aggressive, doctrine-enforcing cardinal before he was appointed to the Vatican top job – also defended the Church's right to 'speak of human nature as man and woman, and ask that this order of creation be respected'.
Vatican spokesman: Father Federico Lombardi said the Vatican continues to condemn the use of the death penalty
The Catholic Church teaches that homosexual acts are a sin. It opposes gay marriage and, in October, a leading Vatican official called homosexuality 'a deviation, an irregularity, a wound'.
This month the Vatican opposed a proposed UN declaration, backed by all 27 European Union states, calling for an end to the practice of criminalising and punishing people for their sexual orientation.
The declaration was seen as an important condemnation of countries such as Iran and Saudi Arabia, where homosexuality can be punished by death.
A Papal spokesman was later forced to clarify that the Vatican continues to condemn the use of the death penalty for any crime, including any related to homosexuality.
Instead, the Vatican said its opposition to the UN proposal was driven by concern that countries that prohibit gay marriage would somehow be targeted.
The Italian gay rights association Arcigay branded this an 'excuse' to distract people from the real intent of criminalising gays.
The Pope also used yesterday's address to criticise the idea that he is seen by the young as some form of rock star.
He said Christian gatherings such as World Youth Day should not be seen as 'a sort of rock festival modified in an ecclesiastical sense'.
The week-long youth festival in July culminated in a mass celebrated by Benedict in Sydney, attended by some 350,000 people.
