As he left the police station, Cardinal Joseph Zen Ze-kiun asked people to pray for democracy in the city.
"To seek to re-define the nature of marriage would be to undermine it as the fundamental building block of our society," the Irish bishops' conference said.
Tens of millions of people are "in chains" because of human trafficking and forced labor, and it leading to their "dehumanization and humiliation," the pope said.
Since the Decree of Ecumenism, it is not a case of everyone converting to Catholicism but of "us all being able to learn from one another."
Retired Hong Kong Cardinal Joseph Zen says he will be risking arrest by Chinese authorities Wednesday, joining leaders in the months-long Occupy protests there who are handing themselves over in a bid to stop violence against the protesters.
According to reports by Hong Kong public broadcaster RTHK Tuesday, Zen said he would be joining three of the Occupy group leaders in turning themselves in.
World leaders are expected to negotiate terms of a potential carbon-cutting agreement to be signed in 2015.
Pope Francis met with a group of some 50 young refugees from conflicts throughout the Middle East Sunday evening here, before ending his three-day trip to Turkey and heading back to Rome.
Telling the young people -- who had fled violence in places such as Syria, Iraq, and other parts of Turkey -- not to be discouraged, the pontiff promised that he and the Catholic church are with them in their struggles.
Istanbul -- Pope Francis: "The one thing that the Catholic Church desires, and that I seek ... is communion with the Orthodox Churches."
Istanbul -- Visiting an ancient Christian community, Pope Francis called on the church to "throw off defensiveness" to overcome misunderstanding.
Istanbul -- Speaking to Turkish leaders Friday, Francis said the "grave conflicts" in Iraq and Syria "cannot be resolved solely through a military response."