Pope Benedict XVI has described family values as the foundation of world peace in his New Year's Day Mass.
The Pope says the family is the "primary agency of peace"
"The family is the first and indispensable teacher of peace," the Pope told worshippers at St Peter's Square in Rome.
The pontiff said that "whoever, even unknowingly, circumvents the institution of the family undermines peace in the entire community".
Pope Benedict has made defending the traditional family a priority.
The Vatican opposes granting legal recognition to gay and unwed couples, though the Pope did not touch on such controversies directly in his New Year prayer on Tuesday.
"Everything that serves to weaken the family based on the marriage of a man and a woman... constitutes an objective obstacle on the road to peace," he said.
His message followed a pro-family rally by hundreds of thousands of Spanish Catholics on Sunday, which he had addressed via a video link.
His New Year prayer included a plea for renewed global efforts to dismantle nuclear weapons and curb the arms trade.