It would be easy to write these people off as extras . And 20 years ago, the last time I was at such an event, the people in attendance were mainly highly trained performers who held aloft placards that spelled out different messages, North Korea–style. But Tuesday’s crowd was different. It was made up of university professors, scientists, administrators, bureaucrats and people who had made some sort of contribution to the state. They weren’t props but excited participants who expected to remember this day.

I noticed that right away when I walked past a raised platform covered with artificial grass that surrounded a big television screen. People were crouching down next to the platform and neatly arranging their letter of invitation, parade-picture ID and program, almost all in the same fashion, like sacraments on a church altar. Then they would snap a picture, aiming their camera s so that China’s national symbol, the Gate of Heavenly Peace, appeared in the background. These were photos designed to be boasted about on social media: “Guess where I was today?” “Yes, at Tiananmen Square.” “Yes, at the ceremony.” And here is proof.

If these were their sacraments and this ceremony was their ritual, what then was their belief?

That would probably be the message broadcast on the giant screens that surrounded us. Before the parade began, those screens showed archival footage of the past 70 years presenting a story about how China had been poor and beaten down by outside powers until the Communist Party saved the country .

The Mao era wasn’t portrayed as foreign journalists and academics often depict it — a series of violent campaigns against imagined enemies of the state and the worst famine in recorded history — but as a period of pioneering glory, when China secured its borders for the first time in a century, built a heavy industrial base and set the stage for its economic takeoff.

Raised on this ideology, the attendees seemed visibly moved when soldiers carrying the national flag goose-stepped from the Monument to the People’s Heroes at the center of the square down to the enormous flagpole. I was unnerved by the background barrage of artillery and the amplified sound of the boots striking the pavement — it felt like an invasion of giants — but many people around me stood solemnly. This wasn’t stage-managed: Some looked bored, others gazed around, kids played . But many more looked earnest, just like Americans do when they stand up, hand on heart, for the national anthem at a sports event.