That’s hardly surprising given the taut history between the two men. More than a year ago, Francis criticized Trump’s proposal to build a wall on the southern border with Mexico — and the then-candidate for the White House shot back. Francis said in February 2016 that anyone who focused on building walls rather than bridges “is not Christian.” Trump, who at that point was still seeking the Republican presidential nomination, took to Facebook to respond.

“If and when the Vatican is attacked by [the Islamic State in Iraq and Syria], 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,” he wrote.
Trump also said that it was “disgraceful” for a “a religious leader to question a person’s faith.”
That was only the most memorable of the run-ins between two leaders who seem like polar opposites in virtually all respects.

Francis’s efforts to show his modesty have not always sat well with the commander in chief. Back in 2013, Trump complained on Twitter that he did not like seeing the pontiff standing in line to pay his hotel bill. “It’s not Pope-like!” the future president said. Trump's views on pontifical decorum appear fluid. Asked by a Twitter user the following year who his first choice would be as a participant on NBC’s “Celebrity Apprentice,” Trump responded, “The Pope!”

Francis himself has kept his focus on more somber matters. He has emphasized the importance of social justice in his teachings and has offered critiques of capitalism itself. In his criticisms of “profits at any price,” some free-market American conservatives have detected a socialistic worldview. In 2016, Francis said that one of the causes of “terrorism” was a “world economy [that] has at its center the god of money and not the person.”