The message during the Pope's celebration of Epiphany is the latest in a series of remarks largely seen to be rebukes to David Cameron and other world leaders attempting to introduce same-sex marriage.

Under increasing attack because of outspoken opposition to homosexual marriage, the 85-year-old pontiff said that church leaders must resist efforts to change just to suit public pressure.

"Today's regnant agnosticism has its own dogmas and is extremely intolerant regarding anything that would question it and the criteria it employs," the Pope said before a gathering of 10,000, which included outgoing prime minister, Mario Monti, who has avoided expressing an opinion on gay marriage.