Pope Francis on Sunday encouraged people of different religions to work together in caring for the Earth, which he called our "common house."
Speaking from his window in a Vatican palazzo to tens of thousands of pilgrims and tourists, Francis singled out a few hundred people who had marched to St. Peter's Square under the banner "One Earth, one family."
The marchers included Christians, Muslims, Jews, Hindus and others who had walked from near the French embassy to remind people of a key U.N. climate change conference in Paris in December.
"I encourage the collaboration between persons and associations of different religions on behalf of an integral ecology," Francis said, offering good wishes to young people discussing what he described as "the care of the common house."
In a recent encyclical, or church teaching document, about the environment, Francis wrote passionately about the world's moral duty to save the Earth and move away from business systems that pollute.
For Francis, efforts to preserve the environment are an excellent way to bring together secular and non-secular forces, and especially members of various religions. Love for the environment also expands his papal agenda of highlighting social justice issues like poverty.
In his encyclical, Francis noted how the poor often suffer the most from pollution and from other environmental damage in developing countries.
The Vatican is putting on a panel Wednesday to draw attention to a conference in Rome later in the week being organized by the Pontifical Council of Justice and Peace and by Catholic groups that work on development issues.
Scheduled to join a Vatican cardinal on the panel is Naomi Klein, an author whose recent book "This Changes Everything: Capitalism vs. the Climate" explored the relationship between economic powers and the environment.