Francis issued his toughest condemnation to date of the weapons industry at a rally of thousands of young people at the end of the first day of his trip to the Italian city of Turin.
"If you trust only men you have lost," he told the young people in a long, rambling talk about war, trust and politics after putting aside his prepared address.
"It makes me think of ... people, managers, businessmen who call themselves Christian and they manufacture weapons. That leads to a bit a distrust, doesn't it?" he said to applause.
He also criticized those who invest in weapons industries, saying "duplicity is the currency of today ... they say one thing and do another."
Francis also built on comments he has made in the past about events during the first and second world wars.
"The great powers had the pictures of the railway lines that brought the trains to the concentration camps like Auschwitz to kill Jews, Christians, homosexuals, everybody. Why didn't they bomb (the railway lines)?"
Discussing World War One, he spoke of "the great tragedy of Armenia" but did not use the word "genocide".
Francis sparked a diplomatic row in April calling the massacre of up to 1.5 million Armenians 100 years ago "the first genocide of the 20th century," prompting Turkey to recall its ambassador to the Vatican.