Pope Francis called on atheists to unite with believers of all religions and work for "a homemade peace" that can spread across the world, while celebrating his first Christmas as Roman Catholic leader, Reuters reported.

Pope Francis spoke to nearly 70,000 people from the central balcony of St. Peter's Basilica. He also made an appeal for the environment to be saved from "human greed and rapacity, Reuters reported.

"Peace is a daily commitment. It is a homemade peace," Francis said from the same spot he emerged as leader on March 13, Reuters reported.

He said that on this day, people of other religions were also praying for peace, and  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, according to Reuters.

Reuters reported that Francis's reaching out to athiest and people of other religions is a "marked contrast" to former Pope Benedict, who gave off the impression that he saw non-Catholics as second-class believers.

Pope Francis also called for "social harmony in South Sudan, where current tensions have already caused numerous victims and are threatening peaceful coexistence in that young state." Thousands are believed to have died in violence divided along ethnic lines between the Nuer and Dinka tribes in the country, which seceded from Sudan in 2011 after decades of war.

The Pope also called for dialogue and communication to end the conflicts in Syria, Nigeria, Democratic Republic of Congo and Iraq, and prayed for a "favorable outcome" to the peace process between Israelis and Palestinians.

"Wars shatter and hurt so many lives!" he said, saying their most vulnerable victims were children, elderly, battered women and the sick.