Pope Francis implied on Thursday that Republican presidential candidate Donald Trump is "not Christian," referring to his political views on immigration from Mexico.
Reporters asked the pope about Trump's comments on the issue as he was on his way back to Rome from Mexico, reminding statements media mogul made about building a wall between US and Mexico.
"A person who thinks only about building walls, wherever they may be, and not building bridges, is not Christian," Francis responded, adding that "This is not in the gospel."
Trump responded swiftly to the Pope’s comments about him at a campaign event in South Carolina, saying, "For a religious leader to question a person’s faith is disgraceful."
He added, "No leader, especially a religious leader, has the right to question another man’s religion or faith."
Trump later put a statement on his Facebook page in response to pope.
The reporters asked whether he would like to recommend a presidential candidate to American Catholics.
He refused, saying, "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."
Trump has promised that if he wins the presidential election taking place in November this year he will deport millions of illegal immigrants.
Last week he said in a televised broadcast that Pope Francis doesn't understand the issue.
"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," he said.
Francis said, "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."
The pope quickly became the top-trending topic on Twitter in the United States after news of his comments came out around noon EST (1700 GMT).
The leader of the world's Roman Catholics was winning the battle on social media: Overall sentiment for Trump was negative, while overall sentiment for Francis was positive, according to social media analytic firm Zoomph.