We saw Jesus rise from the dead, and then 30 minutes later it happened again. The crowd stood transfixed as a vast, hydraulic Messiah emerged from the fibreglass mountain and Handel's "Hallelujah Chorus" boomed from loudspeakers. Towering over us, he closed his eyes, wiggled his hands and turned jerkily to the left, then to the right. A huge roar of noise as an aeroplane came in to land a few yards away added a supersonic feel to the miraculous event.
On the ground, a girl crossed herself and kissed her hand. Her mother wiped away a tear. Church bells tolled - presumably they were big on them in Jesus's day - and the largely Brazilian crowd clapped and cheered enthusiastically. Then, as their risen lord began to retract back into his mound, they rushed off to see the Last Supper.
This was Tierra Santa (the Holy Land), and you can find it jammed between the Aeroparque airport in Buenos Aires and a waterworld. It describes itself as the world's first religious theme park and, in a continent full of surprises, it was the most surreal experience of my six-month trip across South America.
Argentina has long been a favoured destination for the British and Buenos Aires provides many of the diversions of a European city: an appealing café culture with a great arts scene and nightlife. Drawing on their Italian and Spanish heritage, porteños, as the citizens of Buenos Aires are called, seem incredibly cool and chic, yet they are immensely hospitable, too. Get a map out on the corner of this capital's streets and within minutes someone will be at your elbow, offering help.
In some quarters of the city there are signs of great affluence, despite the privations of the economic crash of 2001 that wiped out virtually everyone's savings. But a vast shanty town next to Retiro, the main coach station, is a reminder of just how poor some people are. I visited another notorious slum called Villa 15, where people live in shocking poverty and where crack cocaine is cheaper to buy than beer. If you're wealthy, though, you can have everything you could possibly want delivered to your door, including, it seems, Jerusalem.
Arrive at the entrance of Tierra Santa and you will be greeted by staff done up in what a Hollywood director might kid himself is period Middle Eastern garb. A young woman - maybe she was supposed to be Mary Magdalene - took my money, then a Roman soldier sternly checked our tickets and we climbed Golgotha to see the Crucifixion. At the top was a fibreglass Jesus nailed up between two criminals. At their feet another Roman soldier, this time a model, was eating a chicken drumstick in the manner of someone pleased at a job well done.
Next, the Sacred Heart: a representation of Jesus's head and shoulders, about the size of a Land-Rover, located under Golgotha. The brightly illuminated heart was situated, somewhat unbelievably, just under his Adam's apple.
Then we were off to see the the Nativity, another feat of lighting and hydraulics. The story was narrated by one of those über-macho voices that will be forever associated with 1970s Old Spice adverts. To the strains of "Silent Night", the guiding star sprinted across the ceiling, arriving at the stable a nose behind the Magi, which just goes to show how wise they really were.
As time was getting on, we made for the Creation - quickly taking in the Resurrection one more time en route - to see how it all began. And verily there was a rather good laser display set to a tune by Enya.
To get the full effect from a visit to Tierra Santa you have to go after dark, so you can properly enjoy the special effects and period costumes as you walk through the gloom of the fibreglass alleys. And don't forget to spare some time for the authentic live dance show in the main square, which was mercifully rained off the night we were there.
During Holy Week, thousands will come to see some of the main events of Jesus's final hours played out by actors. Indeed, since it was founded in 1999, Tierra Santa has had millions of visitors file through its gates - some devout believers, others sniggering cynics there for an utterly kitsch experience.
Middle-class porteños regard the theme park as extremely corny. This is, after all, a nation that takes its religion seriously.
Peter Johnson, business editor of the English-language daily the Buenos Aires Herald, speculates: "Maybe the theme park took off here because of the Jewish-Muslim-Christian mix that there is in Buenos Aires, where they seem to get on quite well with each other, unlike other parts of the world."
But somehow Tierra Santa seems completely out of place in this city. There are many parts of South America where a theme-park treatment of faith would sit more comfortably.
In Bolivia, by the side of Lake Titicaca, we witnessed a priest blessing people's cars and trucks with holy water. At the Witches' Market in La Paz, people buy llama foetuses to bury in the foundations of new homes as a measure of protection against evil spirits. (This in a country where well over 90 per cent of the people call themselves Christians.) There, as in Peru and parts of Argentina and Chile, Catholicism and indigenous beliefs often intermingle. Many of Tierra Santa's visitors come from outside the country; on the day we went, there were big parties of ultra-religious Brazilians.
As to who financed the theme park, I'm told that Tierra Santa's backers prefer to remain in the shadows, although the person who made many of the models is an eccentric called Fernando Pugliese. His website says he was first approached about the project by the Union of Shopworkers in 1998.
However it came about, it is one of the most entertaining evenings you can spend in Buenos Aires. And for all those Brazilian visitors, it's a far more cost-effective pilgrimage than going all the way to Jerusalem.