Pope Francis in Policymakers abroad

On Environment: Avert serious effects of environmental deterioration

I call for a courageous and responsible effort to redirect our steps and to avert the most serious effects of the environmental deterioration caused by human activity. I am convinced that we can make a difference, I'm sure. And I have no doubt that the United States, and this Congress, have an important role to play.

On Environment: Amazon is not an inexhaustible source of resources

"We know of the suffering caused for some of you by emissions of hydrocarbons, which gravely threaten the lives of your families and contaminate your natural environment," he said.

There are movements, the pope told a stadium with some 4,000 people from the Amazonian region, trying to preserve the forest that also "hoard great expanses of woodland and negotiate with them, leading to situations of oppression for the native peoples." Saving the trees and wildlife, in other words, is not good enough, if the people who live in the region are not equally protected.

On Families & Children: No ideological colonization of contraception & abortion

That's a highly sensitive issue in Peru, since former President Alberto Fujimori launched a family planning program in 1996 that involved the sterilization of thousands of women. Justified at the time by a desire to reduce poverty, the program stirred controversy when many women, mostly members of the country's Amazonian indigenous groups, reported that they had been sterilized without their consent.

On Immigration: It's not Christian to build a wall on US-Mexican border

The rare back-and-forth between pontiff and presidential candidate underscored the popular pope's willingness to needle U.S. politicians on hot-button issues. Francis' comments came hours after he concluded a visit to Mexico, where he prayed at the border for people who died trying to reach the U.S. He was asked what he thought of Trump's campaign pledge to build a wall along the entire length of the border. "A person who thinks only about building walls, wherever they may be, and not building bridges, is not Christian," he said. While Francis said he would "give the benefit of the doubt" because he had not heard Trump's border plans independently, he added, "I say only that this man is not a Christian if he has said things like that.

On Immigration: We should receive asylum-seekers, not reject them

He spoke at length about immigration, a controversial issue in Europe as well as the US. The populist Italian government has refused port access to non-government ships that have been rescuing asylum-seekers trying to cross to Italy from Africa in flimsy boats.

"I believe that you cannot reject people who arrive. You have to receive them, help them, look after them, accompany them and then see where to put them, but throughout all of Europe," Francis said.

"Some governments are working on it, and people have to be settled in the best possible way, but creating psychosis is not the cure," he added. "Populism does not resolve things. What resolves things is acceptance, study, prudence."

On Immigration: Opposes border wall between US and Mexico

Trump fired back via Facebook: "If and when the Vatican is attacked by ISIS, which as everyone knows is ISIS's ultimate trophy, I can promise you that the Pope would have only wished and prayed that Donald Trump would have been President because this would not have happened. ISIS would have been eradicated unlike what is happening now with our all talk, no action politicians."

Trump added, huffily, "No leader, especially a religious leader, should have the right to question another man's religion or faith."

On Immigration: Grave sin not to offer aid to migrants

The pope has spoken frequently about the treatment of migrants over his 11-year papacy. Migrants crossing the Mediterranean Sea in simple crafts or home-made dinghies from northern Africa and the Middle East have been the subject of intense debate across Europe over the past decade.

In recent weeks, the pope had been offering a series of reflections about Catholic spiritual matters in his weekly audiences. The pope said he was postponing that series this week, to consider "people who are crossing seas and deserts to find a place where they can live in peace and security".