The 2016 Scottish Church Census, performed by Brierley Consultancy, found 390,000 regularly attended church in 2016. This compares to 854,000 in 1984. This is mirrored by a decline in congregations, from 4,100 in 1984 to 3,700 in 2016.
Aberdeenshire was the only place in Scotland bucking the trend, with 350 more people attending church in 2016 compared with 2002.
If the current decline continues, less than 300,000 Scots will be regularly attending in 2025.
The age of regular Scottish churchgoers is also a concern. The census found 42 per cent of them are aged 65 or above - twice the proportion of the Scottish population as a whole. The census said this "has obvious implications for the future".
Immigration has been credited with propping up some churches in Scotland.
For example there are now 25 Polish churches in Aberdeen and Aberdeenshire, and attendees at Pentecostal churches have almost doubled since a previous census in 2002. The number now stands at 19,000 - 5 per cent of all churchgoers in Scotland.
Consultant researcher Dr Peter Brierley noted: "The result of the 2016 Scottish Church Census will be disappointing for most church leaders, but a forecast based on the results of the 2002 Census would give an estimate of 350,000 by 2016, so the actual result is better than expected, 11% higher, partly as a result of the numbers of immigrants coming into Scotland, and the growth of the Pentecostal churches."
