"Every effort must be made to eradicate this shameful and intolerable crime (of human trafficking)," Pope Francis said.

The pope called on journalists to stop feeding the "vicious cycle of anxiety" and "spiral of fear."

The pope asked Assad "to ensure that international humanitarian law is fully respected with regard to the protection of the civilians and access to humanitarian aid."

"We are united in the blood of our martyrs," Pope Francis said.

Pope Francis said the "richest experience" of the church operating in a way that is not strictly "top down" came from the two meetings of the Synod of Bishops on the family.

"A rigidity that is far from a discernment of situations has been introduced" in seminaries, Pope Francis said. He also called clericalism "one of the most serious illnesses that the church has."

Doubts can be "a sign that we want to know God better and more deeply."

Pope Francis said the visit with women rescued from human trafficking and his visit to a neonatal ward were stands out in a Year of Mercy.

Pope Francis praised the 100 countries that joined the Paris climate agreement but emphasized that implementing it must involve multidisciplinary cooperation and special measures of solidarity with the poor.

After not receiving a response from the pope, the cardinals released their letter to the public.