The latest person to find himself on the receiving end of Donald Trump's insults isn’t an American politician — it’s the leader of the Catholic Church.When asked Thursday about the Republican hopeful’s plans to build a wall along the U.S.-Mexico border, Pope Francis said that building walls is “not Christian,” the Associated Press reported."A person who thinks only about building walls, wherever they may be, and not building bridges, is not Christian," he said. "This is not in the Gospel."He also stated that since he had not heard details of Trump’s plan, he would give the businessman the benefit of the doubt. Pope Francis' statement wasn’t enough to avoid a response from the notoriously thin-skinned candidate, however. A few minutes after the pontiff’s comments were reported, Trump had posted a statement to his website, which began by suggesting that the Vatican was likely to be attacked by terrorists.“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 [p]resident, because this would not have happened,” the statement began. Trump also defended his Christianity, saying that for a religious leader to question a person’s faith is “disgraceful.” He also stated that Pope Francis was being used as a “pawn” by unnamed parties.Trump had previously declared the religious leader to be “ very political ” for his plans to pray for refugees in Mexico. As part of his recent trip to Mexico, the Pope went to the U.S.-Mexico border to offer prayers for those who had died trying to cross into the United States.The recent attacks on Pope Francis are a big reversal from Trump's previous opinion. Back in 2013, the Donald posted his approval of Francis on Twitter.