Pope Francis "trusts that the immense and immediate needs of so many individuals and communities will continue to inspire a vast outpouring of solidarity and mutual aid in the best traditions of the nation."

The forthcoming joint message will ask people of all faiths "to adopt a respectful and responsible approach toward creation."

Throughout the Gospels, Jesus is like an "arsonist," the pope said, setting people's hearts ablaze.

Mr. Spicer, a Catholic, had expressed a desire to meet Pope Francis in May, but he was left off the list of U.S. officials who accompanied President Trump to the Vatican.

The pope said that church teaching can contribute to a more humane and just society, but only if the church is allowed a voice in answering "the great questions of society in our time."