I’m on my way to Cocharcas, a town in the southern Peruvian Andes. As I bump along in a crowded minivan, I run through some questions in my head. They relate to my research into local cults and pilgrimage and they explain why I am here. The biggest question is: how can we explain the fact that a religion so alien to the Andes as Catholicism became so popular, to the point that today it is held as a marker of the region’s identity?

Legend has it that in the late 16th century a humble man travelled from his native Cocharcas to the shores of Lake Titicaca, about 500 miles away, to acquire a replica of Our Lady of Copacabana, a famed Marian devotion, and took it back to his hometown. Shortly after arriving in Cocharcas, the icon began to display beneficial powers and soon the locals made it into their patroness. Thus was born Our Lady of Cocharcas. In the 17th century Jesuit missionaries promoted the cult, and encouraged their parishioners to build a magnificent church, so large that it dwarfs the surrounding buildings. For centuries, pilgrims from different corners of Peru have arrived every year to celebrate Our Lady’s birthday on 8 September.

The road to Cocharcas is dusty and narrow. The driver stops at a small restaurant where we have a quick bowl of soup. It is imperative to arrive before nightfall because the vigil held on the eve of the festival is one of the most important parts of the event. Cocharcas has a couple of modest restaurants and no hotel. The town is crowded and a banner reminds visitors that drinking is prohibited. Lack of alcohol, in combination with the religious fervor, might explain the peaceful atmosphere. People congregate in the church to see the image of Our Lady; a tiny statue with rosy cheeks and long, curly hair, dressed in richly embroidered clothes and sitting atop a portable altar decorated with dozens of energy-saving light bulbs.

Tomorrow the image will be paraded around the plaza. Today nuns and priests take turns leading the crowd in prayers, intended to have a reciprocal effect: Mother of God, pray for us. A succession of masses in the local language, Quechua, runs until midnight. Outside, brass bands play regional music as troupes of dancers perform in honor of Our Lady. A group of artisans finishes preparing the fireworks: no religious feast in the Andes is conceivable without them; people inspect the tower in the main plaza, trying to figure out what will be on display this year.

Pilgrims visit the small chapels housing miniature replicas of the revered image, and light candles, symbolising their requests to Our Lady: health, money, a job, the ease of pain and suffering. Mother of God, pray for us. Though it’s not late, many people get ready to sleep. I quickly reserve a spot on the grassy and crowded churchyard. I watch the sky as I hold on to the small rucksack containing my few possessions, and try to sleep surrounded by strangers.

I am awoken by what sounds like thunder and lightning, but I soon realise that it’s the sound of fireworks. The church bells toll furiously, the bands play, the crowd in the church prays harder, and the multitude in the plaza starts singing…Happy Birthday! It’s midnight. It’s the Nativity of the Virgin all have come to celebrate. The sacred, I think, is perhaps at the crossroads of the trivial and this intense, universal excitement. It is manifest in this overwhelming sense of wonder, in this thundering way of expressing hope. I feel closer to understanding why so many people undertake the long, difficult journey to this place: I am so happy to be here.