The Pontiff said humanity needed to listen to the "language of creation" to understand the intended roles of man and woman and that behaviour beyond traditional heterosexual relations was a "destruction of God's work".
He called on the Church to protect man from the "destruction of himself" saying that tropical rainforests deserved protection but man as a creature "does not deserve any less".
But the Rev Sharon Ferguson, chief executive of the Lesbian and Gay Christian Movement, described his remarks 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."