He said that people of other religions were also praying for peace, and – departing from his prepared text – he urged atheists to join forces with believers.

“I invite even non-believers to desire peace. (Join us) with your desire, a desire that widens the heart. Let us all unite, either with prayer or with desire, but everyone, for peace,” he said, drawing sustained applause from the crowd.

Francis’s reaching out to atheists and people of other religions is a marked contrast to the attitude of former Pope Benedict, who sometimes left non-Catholics feeling that he saw them as second-class believers.

He called for “social harmony in South Sudan, where current tensions have already caused numerous victims and are threatening peaceful coexistence in that young state”.