Pope Francis attacked Republican front-runner Donald Trump Thursday as “not a Christian.” Aboard his plane, the pope was asked specifically about comments Trump made about the Pope’s visit to the Mexico border. The pope did not mince his words.

A person who thinks only about building walls, wherever they may be, and not of building bridges, is not Christian. This is not the Gospel. As far as what you said about whether I would advise to vote or not to vote, I am not getting involved in that. I say only this man is not Christian if he has said things like that.

Breitbart’s Alex Swoyer, live from Trump’s latest South Carolina rally, reports Trump’s response:

[The Pope] actually said that maybe I’m not a good Christian, which is really not a nice thing to say. 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. — — The pope only heard one side of the story. He didn’t see the crime, the drug trafficking and the negative economic impact the current policies have on the United States. The Mexican government its leadership have made many disparaging remarks about me.

REMINDER: The Pope lives in a Vatican City surrounded by towering walls.

If the translation is correct, the Pope is going way beyond “Who am I to judge?” (his famous comments about homosexuals) to declaring a man “not a Christian” over one issue. To condemn an entire man over this one issue, especially when the Pope himself lives behind towering walls, is hard to grasp.

UPDATE: Ben Carson joined Marco Rubio and Jeb Bush in defending Trump:

“It would be hilarious if it weren’t so sad,” Carson said. “We’ve seen this before in history where people get distracted and don’t look at what’s important. They lose their vision.” Carson refused to comment, however, on whether Trump’s public conduct means he is not a true man of faith. “I’m not going to judge Donald Trump in terms of whether he’s a Christian or not,” said Carson, a Seventh Day Adventist. “Certainly some of the things that he does may not be suggestive of Christianity, but then again, all of us have weaknesses and shortcomings,” he added of Trump, a Presbyterian. “That’s what it’s all about.”

The Carson campaign later released a statement:

“I have spoken often about the need for faith and compassion in America. However, enforcing our immigration laws is not in contradiction with love and kindness. As Christians, we are called to love our neighbors. But as a nation, we must also defend our sovereignty and security. Ending human trafficking into America can save lives and protect the weakest of society from exploitation; and working with Mexico and other Central and South American nations to improve their own governments and economies is a greater service to others than opening our borders.”

UPDATE: Jeb defended Trump and a border wall. “I think the Pope said Trump is un-Christian. That’s between him and his Creator … it is not un-Christian to protect your border, to keep people out who come here illegally.”

UPDATE: Rubio pushed back against Pope: “Vatican City controls who comes in, when they come in, and how they come in, as a city-state. The United States has a right to do that, as well.”

UPDATE: Trump’s full official statement:

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. The Mexican government and its leadership has made many disparaging remarks about me 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. The Pope only heard one side of the story – he didn’t see the crime, the drug trafficking and the negative economic impact the current policies have on the United States. He doesn’t see how Mexican leadership is outsmarting President Obama and our leadership in every aspect of negotiation. For a religious leader to question a person’s faith is disgraceful. I am proud to be a Christian and as President I will not allow Christianity to be consistently attacked and weakened, unlike what is happening now, with our current President. No leader, especially a religious leader, should have the right to question another man’s religion or faith. They are using the Pope as a pawn and they should be ashamed of themselves for doing so, especially when so many lives are involved and when illegal immigration is so rampant.

Follow John Nolte on Twitter @NolteNC