Vietnamese census and survey figures record something in the region of four fifths of the population as having no religion. Taken at face value this would make Vietnam one of the least religious countries on earth. It is a measurement artefact.
What the category counts is affiliation with a recognised organised religion: Buddhism, Catholicism, Protestantism, Cao Dai, Hoa Hao. What it cannot count is a household that keeps an ancestral altar, brings fruit and incense to it at the new moon and the full moon, attends the village dinh at the tutelary spirit's festival, consults a medium when a business fails, and would answer a survey question about religion with a straightforward no. That household is doing what most Vietnamese households do.
The problem is the survey instrument, and it is the same instrument that produces implausible irreligion figures across East Asia. It asks about belonging in a form built for exclusive-membership religions, in societies where the practices in question have never had membership, clergy, doctrine or a name that ordinary people use for them.
Two consequences follow for anything written here:
- No adherent figure for Vietnamese folk religion should be quoted with confidence, in either direction. The low numbers measure the category and the high numbers are extrapolations from observed practice.
- The state's own position has moved. Len dong was suppressed as superstition for decades after 1954 in the north and after 1975 nationally, tolerated from the late 1980s under doi moi, and then endorsed in a form the earlier policy would not have recognised when UNESCO inscribed the Mother Goddess practices as intangible cultural heritage in 2016. What had been superstition became heritage without any change in what people were doing.