The people of the Sierra Norte have achieved a rare balance – preserving an ancient way of mountain life while welcoming visitors

When I reach the mountaintop chapel, I slump on the dry stone wall, wheezing in the thin air, marvelling at what combination of brawn and piety must have been needed to build such a thing at such a height. It might not be a Sunday, but I can tell that mass at 3,000 metres must be magnificent. Open walls reach out to the rolling slopes of the Sierra Norte, 35 miles east of Oaxaca City in southern Mexico, with virgin pine in every direction. Somewhere unseen, a brown-backed solitaire bird lifts a lonely song over the valley. Then comes the bark of warring crows and, most exciting of all, the quick peeps of a hummingbird, believed here to ferry messages between the living and dead. At this height, even to a heathen like me, the urge to pay tribute is understandable.

My guide, Eric, who must have a third lung, judging by his ability to tell stories on the climb, becomes quiet and crosses himself before the altar. I’m a little surprised at this show of devotion. Down in the small town of Tlacolula de Matamoros, he had shown us a site the Indigenous Zapotecs used to praise the sacred mountain above – before the Spanish came and plonked a church on the same spot. The colonialists’ intention, Eric explained, was erasure. But when conversion comes at the point of a sword, some resistance seems inevitable. Here, Indigenous signs hide in Catholic icons. Dark stones in holy corners hold animist engravings. Duality is everywhere. Praise whispered in the name of the Virgin of Guadalupe, the mother of Christ to Mexican Catholics, is also meant for Huitzilopochtli, the old sun god.