To robust applause from the gathered faithful, Pope Francis called Sunday for a day of prayer and fasting over the violence in Syria.
Devoting the totality of his weekly remarks in St. Peter's Square to the civil war in Syria, Francis invited "all men of good will" to join with Catholics on September 7 to take part in the prayer and fast.
He condemned in strong and personal terms the recent use of of chemical weapons.
"I tell you that those terrible images from recent days are burned into my mind and heart," Francis said. "There is a judgment of God and of history upon our actions which is inescapable!"
The pontiff urged a peaceful ending to the conflict. "Never has the use of violence brought peace in its wake," the pope said, his voice rising. "War begets war, violence begets violence."
In recent days the United States, Britain and France have had high profile debates about the merits of military intervention in Syria.
Britain's parliament dealt a blow to Prime Minister David Cameron's desire for military action.
In the United States, President Barack Obama announced his intention to get congressional approval for any military involvement.
The French government is expected to discuss the matter early next week.
While Francis did not mention any of those efforts specifically, he called on the "international community to make every effort to promote clear proposals for peace in that country without further delay, a peace based on dialogue and negotiation."
On Sept. 7, he said, people will gather at St. Peter's Square from 7 p.m. to midnight, while other churches hold similar community events.
"Humanity needs to see these gestures of peace," he said.