Fifty-eight per cent of Scots now say they have no religion, a record level, and up from 40 per cent in 1999, the Scottish Attitudes Survey revealed.
Amongst major denominations, the Church of Scotland (Kirk) has seen the sharpest decline, with just 18 per cent saying they belong to the Kirk. The Church of Scotland figure for 1999 was 35 per cent.
The survey found the proportion of Roman Catholics (10 per cent), other Christian affiliations (11 per cent), and those of non-Christian faiths (2 per cent) have remained stable within the Scottish population.
Young people were significantly more likely to be irreligious than older people. Around three-quarters of young people (74 per cent of 18-34s) say they have no religion compared with 34 per cent of those over 65.
Ian Montagu, a researcher at ScotCen, said: “The decline in religious identity in Scotland has been most keenly felt by the Kirk as fewer and fewer people choose to describe themselves as Church of Scotland by default.
“As each generation coming through is consistently less religious than the last, it is hard to imagine this trend coming to a halt in the near future.
“However, if the Kirk is able to push through liberalising measures such as allowing ministers to oversee same-sex marriage ceremonies, it is possible that its appeal may broaden somewhat to younger, more socially liberal Scots.”
The 2016 Scottish Social Attitudes survey is based on interviews with 1,237 people between July 2016 and December 2016.
The results come less than a week after the British Social Attitudes Survey revealed Brits, especially Christians, are increasingly more accepting of same-sex marriage, abortion, pornography, and sex before marriage.
Also conducted in 2016, it found a strong majority of the UK public (64 per cent) now say same-sex relationships are “not wrong at all”, up from 57 per cent in 2013 – the year before gay marriage became legal.
On sex before marriage, three-quarters of Brits say it is “not wrong at all”, up dramatically from 42 per cent when the question was first asked in 1983.
Interestingly, Christians appeared to be following the national trend, with a majority now believing there is nothing wrong with sex between unmarried people.
Even amongst Roman Catholics, whose church firmly opposes abortion, 61 per cent said that abortion should be permitted if a woman does not want a child.