Pope Francis made a forceful entry into the immigration debate during his second trip to North America this week, taking on Donald TrumpDonald TrumpFundamentals or euphoria? Both fueled post-election stock surge Freedom Caucus founder: GOP health plan did not meet campaign promises Former US envoy: No good military options against North Korea MORE as he pleaded the case for compassion toward migrants.
Here are some of the key moments from his trip to Mexico:
1. Spat with Donald Trump
Before the pope landed in Mexico, Donald Trump called Francis "a very political person "and said the Mexican government got him to come because they want to “keep the border just the way it is because they’re making a fortune.”
A Vatican spokesman responded, saying "The pope always talks about migration problems all around the world, of the duties we have to solve these problems in a humane manner, of hosting those who come from other countries in search of a life of dignity and peace." Francis made no mention of Trump while in Mexico, and that was that.
Except it wasn't.
Speaking to reporters aboard the papal airliner, Francis responded to a reporter's question about Trump with a bombshell.
"A person who thinks only about building walls, wherever they may be, and not building bridges, is not Christian," he said.
Trump shot back Thursday that it was “disgraceful” of the pope to question his religion.
2. Meeting with Patriarch Kirill
Arguably the most historic moment of the trip took place in an airport, as Francis met an Eastern Orthodox patriarch.
The meeting with Patriarch Kirill of Moscow was the first of its kind since the Great Schism of 1054 — the year the Greek East and Latin West churches split, with Eastern Orthodox and Catholic churches each going their own way.
3. Fashion faux pas
Mexican first lady Angélica Rivera, no stranger to scandal or fashion, irked some conservative Catholics with her fashion choices for the pope's welcome ceremony on Friday in Mexico City.
Rivera was wearing a white dress, a major faux pas for most women in the presence of the pope. Privilege du blanc, "the privilege of the white," is a tradition whereby only certain queens and princesses from Catholic royal families can wear white at a papal reception.
Francis made no mention of Rivera's dress on his flight back to Rome.
4. Use of an indigenous language
"Li smantal Kajvaltike toj lek," Francis said.
Although it was only one phrase that translates to "the Lord's law is perfect and it comforts the soul," Francis' use of the Tzotzil language is significant both for the Catholic Church and for some of its most impoverished parishioners.
The pope's linguistic adventure was a ribbon-cutting ceremony of sorts: From now on, the Vatican will allow masses to be conducted in native languages. The state of Chiapas alone boasts 12 recognized languages.
Local cultures will certainly benefit from unifying their faith and their language, but the Catholic Church has its own reasons for the reform. Chiapas is the Mexican state with the highest level of Catholic attrition: Whereas 81 percent of Mexican adults self-identify as Catholic, nearly half of adults in Chiapas have joined Protestant denominations.
5. Visit both borders
The symbolism of a pope laying a wreath to honor migrants on a platform over the Rio Grande was not lost on anyone, but Francis' visit to Mexico's southern border was a sign that he wasn’t letting the Mexican government off the hook, either.
The "humanitarian crisis," as Francis called North American migration patterns, is not exclusive to the Southwestern deserts of the United States. By scheduling a south-to-north Mexican agenda, Francis mirrored the path of Central American migrants who often face worst abuse.
6. Prison song
In one of the stranger moments of Francis' latest North American jaunt, he was treated to an interesting musical selection while visiting a Ciudad Juárez jail.
As the best-behaved inmates, 20 women and 30 men, lined up to personally greet the pope, the house band with prisoners playing dove into a particularly gloomy, and possibly slightly out-of-tune, rendition of “Bésame Mucho.” No word on whether there was a message hidden in the song selection.
On the other hand, the Argentine may have appreciated the brief respite from the mariachi bands that seemed to appear at his every stop.
7. "Don't be selfish!"
During his stop in Michoacan, a western state beset by drug violence, Francis had more than one occasion to adopt a stern tone.
He consistently railed against superficial temptations pulling Mexico's youth toward a life of organized crime, and even warned members of the church against receiving alms from criminals.
But one young Mexican felt the whole brunt of papal wrath when he almost pulled the 79-year-old pontiff to the ground in an over-eager bout of religious exuberance.
"Don't be selfish, don't be selfish!" Francis said to him.