“A person who thinks only about building walls, wherever they may be, and not building bridges, is not Christian. ... I say only that this man is not a Christian if he has said things like that.”— Pope Francis speaking about Donald TrumpIt was 39 years ago, mid-April of 1978. I was 18 and riding in the open bed of the GMC pickup, along with my friends Eugenio, Lalo and Felipe.Aaron, a 16-year-old from Boston and the only other American, was in the passenger seat beside Gerardo, who was driving the truck that belonged to his dad.Gerardo was a big, handsome and constantly happy guy — he could be a starting linebacker on any high school football team in America, probably looking at a college scholarship. He was our leader and playmaker, our chief minister of mischief.We were young men headed for spring break at a beach on the Gulf of Mexico. It was more than that, we realized. For Aaron and me, it marked the end of our year as Rotary International exchange students, doing our best to soak in our host nation’s culture while trying to remember we were ambassadors for the people who sent us.It was a last hurrah before graduation and the start of our separate, adult lives. That was most poignantly so for Gerardo, who was scheduled to begin seminary studies for the priesthood in May.Our excursion, from the central plateau city of Puebla to the seaside town of Nautla, north of Veracruz, included a side-trip off of Federal Highway 129 into a dense rain forest, where coffee bushes, banana groves and papaya trees surrounded quiet villages of campesino natives all dressed in white cotton, all bearing the prominent facial features of their Mayan ancestors.As we crept along the unpaved single road in one of these villages, some of the campesinos fell in behind the pickup. Neighbors joined them. Several carried the tool of their trade, the machete.They were barefoot. They made no sound. They showed no emotion. There might have been 60 of them. It was eerie.Suddenly, the crowd fell back. I looked to my left, where Felipe sat toying with a large handgun he’d pulled from his duffel bag.Felipe grinned at me. “It’s not loaded,” he whispered.Apparently our Mexican friends had come this way previously and knew what to expect — but they wanted Aaron and me to see this raw, wild sliver of their heritage.I recall the adventure amid the dust-up between Pope Francis and billionaire presidential candidate Donald Trump.Those remote jungle villages were the only inhabited places I can recall in Mexico that did not have walls surrounding them. Everywhere else are walls — around individual homes and neighborhoods; around churches, schools, cemeteries and gardens.Both homes I lived in were surrounded by walls topped with shards glass set in cement. My school had an iron fence topped with spikes. My athletic club was surrounded by a 30-foot wall. Every mercado storefront and tortilleria had a pull-down grate.In my mind, nobody appreciates walls more than the people of Mexico do.It’s Mexico’s heritage. I remember attending Easter Sunday Mass at an ancient church building in Cholula, an Aztec city midway between the Atlantic coast and Mexico City that was conquered by Hernan Cortez. In fact, the church had been built under Cortez’s direction. It had thick stone walls and oversize doors — I was told this was done so mounted conquistadores could ride into Mass and worship without getting down from their horses.It probably mystifies the Mexican people — descendants of Cortez and the native tribes he conquered — that the United States border hasn’t always had a wall to keep them out.If anyone is obsessed with building walls as Pope Francis suggested, I contend it is our neighbor to the south. They respect what a wall suggests — and what the absence of a wall might say, too.As for questioning the Christianity of wall-builders, I’m sure a middle-aged priest named Gerardo might have something to say about that.

Tom Harrison writes editorials for the Butler Eagle.