By Emily Flitter
NEWBERRY, S.C. (Reuters) - Pope Francis assailed Republican presidential candidate Donald Trump's views on U.S. immigration as "not Christian" on Thursday, prompting the billionaire businessman to reprimand the religious leader as "disgraceful" for questioning his faith.
No stranger to controversy, Trump, the longtime party front-runner in national opinion polls, has vowed if elected president to build a wall between the United States and Mexico to keep out immigrants who enter illegally.
In a freewheeling conversation on his flight home from a visit to Mexico, Francis told reporters, "A person who thinks only about building walls, wherever they may be, and not building bridges, is not Christian."
The pope said he did not want to advise American Catholics on whether or not to vote for Trump, and it was not immediately clear what impact his remarks would have on Republicans likely to vote in the Nov. 8 election.
Republican Catholics appear to support Trump more than other Republicans do, according to a Reuters/Ipsos opinion poll.
As of 2014, 71 percent of the U.S. population identified as Christian, 21 percent of them Catholic, according to the Pew Research Center.
Asked if American Catholics should vote for someone with Trump's views, Francis said, "I am not going to get involved in that. I say only that this man is not Christian if he has said things like that. We must see if he said things in that way and in this I give the benefit of the doubt," he said.
Trump, a real estate developer and former reality TV star, said, "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," Trump said in a speech in Kiawah Island, South Carolina, using an acronym for the Islamic State militant group.
"For a religious leader to question a person’s faith is disgraceful," he said. Trump has said on occasion, and again on Thursday, that he is a proud of being Christian but emphasized early in the campaign that he does not talk about his faith as much as others might. He has said his book "The Art of The Deal" is his second most favorite book after the Bible.
"I am a very nice person. And I'm a very good Christian. Because the pope said something to the effect that maybe Donald Trump isn't Christian, ok? And he's questioning my faith. I was very surprised to see it, but I am a Christian. I'm proud of it."
Trump has said he would deport millions of illegal immigrants if he wins the White House. Last week, responding to the pope's plan to visit the U.S.-Mexican border, he said that Pope Francis did not understand the issues involved.
"The pope is a very political person. I think he doesn't understand the problems our country has. I don't think he understands the danger of the open border that we have with Mexico," Trump told the Fox Business Network.
Asked about being called a "political person", Francis said on Thursday, "Thank God he said I was a politician because Aristotle defined the human person as 'animal politicus.' So at least I am a human person."
SOCIAL MEDIA ERUPTS
The pope's remarks and Trump's response lit up social media with many Twitter users speculating on how Trump would move on from the pope's withering comment. Author Dan Dicker @Dan_Dicker tweeted, "Let's see @realDonaldTrump insult his way out of this."
Trump's social media director Dan Scavino @DanScavino tweeted, "Amazing comments from the Pope - considering Vatican City is 100 percent surrounded by massive walls."
Trump accused the Mexican government of making disparaging remarks about him to the pope "because they want to continue to rip off the United States, both on trade and at the border,... and they understand I am totally wise to them."
He said the pope only heard one side of the story and did not see what Trump called the crime, drug trafficking and negative economic impact Mexico's policies had on the United States.
Evangelical Christian leader Jerry Falwell Jr, who has endorsed Trump and spent time with the candidate on his private plane, described him as generous to his employees and family, adding, "I'm convinced he's a Christian. I believe he has faith in Jesus Christ."
Reuters/Ipsos polling since the start of the year shows 43 percent of likely Republican Catholic voters support Trump, compared to 38 percent of Republican voters generally.
(Reporting by Emily Flitter and Steve Holland in South Carolina and Philip Pullella aboard the papal plane; Additional reporting by Anjali Athavaley, Susan Heavey, Chris Kahn, Emily Stephenson, Amy Tennery and Mohammad Zargham; Writing by Howard Goller; Editing by Jonathan Oatis, Toni Reinhold)