Anderson, S.C. -- Donald Trump just took on perhaps a foe even he can't tackle: Pope Francis.

The pope, during a news conference aboard the papal airliner, told reporters, this, according to The New York Times:

"A person who thinks only about building walls, wherever they may be, and not building bridges, is not Christian."

Trump, never one to back down from any fight, was quick to respond. Thus said the Donald on his Facebook page:

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.

Update: 1:30 p.m.:  Marco Rubio, who is Catholic, was asked about the Trump-Francis dust-up before a rally here. Rubio said he wanted to see Francis' full remarks before responding, but said the United States has not just "an obligation, but a right" to control its border.