Of all the people Donald Trump attacked thus far during his eight-month presidential campaign, none have elicited a stronger reaction than his criticism of Pope Francis.

The Republican front-runner concluded Thursday night's CNN town hall by first, wryly, telling Columbia, South Carolina primary voters "the pope is a wonderful guy." Thursday morning, the pontiff told reporters Trump's plan to build a wall along the U.S.-Mexico border is un-Christian and goes against the Gospel.

Trump then called the Vatican ISIS's "ultimate trophy."

"I didn't think it was a good thing for him to say, frankly," Trump said, referring to the wall he would force Mexico to construct. "Somehow the government of Mexico spoke with the pope, they spent a lot of time with the pope, and by the time he left he made a statement."

CNN anchor Anderson Cooper read a portion of Pope Francis' message clarifying that he isn't advocating people to vote one way or another, for or against Trump, only to keep in mind his lack of Christian values. The real estate mogul cited the pope's comments by reminding voters "he's got an awfully big wall at the Vatican."

"I don't like fighting with the pope," Trump said, toning down on his initial reaction. "I think that he heard one side of the story, which is probably by the Mexican government. He didn't see the tremendous strain that the border is causing us with respect to illegal immigration, with the drugs pouring across the border."

Trump praised Pope Francis as someone he greatly respects, but wishes Francis would consult American citizens before criticizing the country's border security measures.

Bullying Candidates and Countries

Asked about a cease-and-desist letter sent to Texas Sen. Ted Cruz, Trump chalked it up to "something I will do on occasion."

He didn't hint at possible litigation, but did say Cruz "has a problem with the truth." Trump cited various examples: an attack ad featuring an interview Trump had with Tim Russert over a decade ago, a photoshopped picture of Florida Sen. Marco Rubio shaking hands with President Obama, and mailers Cruz's campaign sent to Iowa caucus-goers grading them on who they voted for.

Trump added that the Canada-born candidate is already facing another lawsuit, possibly referring to an Illinois case on Cruz's eligibility scheduled for Friday. Cooper asked Trump if his rhetoric - igniting the birther argument, among other candidate's he's attacked - makes him a bully.

"I'm not a bully at all," Trump said, citing his strong personality and business acumen. Cooper followed up by asking if, as president, he would treat countries he doesn't agree with similarly.

"Yeah maybe to China to stop ripping us off. I'd send them to Mexico. And when I say cease-and-desist, maybe it's equivalent. Maybe I do it with my mouth."

Blaming George W. Bush for ISIS

The night's most contentious moment came when an undecided attendee asked Trump why he believes former President George W. Bush lied about weapons of mass destruction in Iraq.

"I'm not talking about lying, I'm not talking about not lying. Nobody really knows why we went into Iraq," Trump said, backtracking on vehement allegation he made during last weekend's GOP debate. "It was not Saddam Hussein that knocked down the World Trade Center."

The attendee pressed Trump to give a concise answer. "So you think the president of the United States, George W. Bush lied? I'm just giving you another shot," he asked. Trump said it may have been the worst a decision a president has ever made.

"The war in Iraq started the whole destabilization of the Middle East," he replied. "It started ISIS. It started Libya. It started Syria. That was one of the worst decisions ever made by any government at any time. In all fairness, Bush made the decision."

"Barack Obama, as bad as he is - and he's bad - and he got us out the wrong way."

Cooper gave Trump one last chance to answer yes or no, to which Trump said he would have to look at some documents.

Jeb Bush Embraces his Latino Family

Former Florida Gov. Jeb Bush's underperforming campaign may see a boost with Hispanic voters heading into next week's Nevada caucus after he openly embraced his Latina wife and completed a full sentence in Spanish.

"SI quieres hacer esta entrevista en Espanol, los hemos," Bush told Cooper. Bush confirmed that his family almost exclusively speaks Spanish at home, calling it an advantage in his life.

"We have a bicultural relationship and it brings a diversity and a joy," Bush said. "It adds a lot of vitality to my life."

As he's done with the other Republican hopefuls participating in CNN's town halls, Cooper asked the candidate how he met his wife, Mexico-born Columba Bush.

Bush said they will celebrate their 42-year anniversary next week, having met in Leon, Guanajuato, Mexico as teenagers.

"I tell people my life can be divided in a lot of ways, but the most important way, perhaps, is A.C. and B.C. - you know, Before Columba and After Columba," Bush said. "And the After Columba part of my life has been a lot better. I'm a lot better person because of it as well."