A major milestone in the religious history of Scotland has been reached.

Scots without a religion form the largest category in the country. The results of the 2011 census, published yesterday, show that 37% of people regard themselves as not belonging to any church or religious tradition. This outnumbers those of each other category.

The degree of change since the last census in 2001 is quite staggering. In that year, 28% had no religion. In 10 years, the nation has shifted from being still solidly Christian in its leaning to one in which religious doubt, uncertainty or outright non-belief are defining the country.

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Fewer and fewer people are willing to state a religious preference, and are instead displaying a dramatic leaning towards a diminishing place for spiritual things in their lives.

It is the Church of Scotland that is suffering the most. Once it was the nation's Established Church, a status that it effectively lost in the 1920s, but even in the 1950s it had 1.3 million members (or 26% of the population).

Since then, it has still claimed a status as "a national church", but its claims to this are badly weakened. In 2001, some 42% of Scots claimed their belonged to the Kirk; now the figure is 32%.

The Catholic Church proportion remains the same at 16%, indicating a much more resilient position. Most smaller religious traditions, including Hindus and others, are not affected by this decline, with the number of Muslims, for instance, increasing by 0.6 of a percentage point to 1.4%.

The rise of those without a religious affiliation represents a sudden shift in Scottish life. Referred to by some sociologists as "nones", the people of no religion are generally not churchgoers, do not pray or baptise their children, and few of them marry in church. Just as their numbers rise, so the moral alignment of the people has changed in respect of assisted suicide, gay marriage and an array of liberal positions on heterosexual behaviour.

The conservative so-called Calvinist morality of 1950s Scotland, with its strict laws on drink, stage and screen censorship, and sexual conduct, has vanished like snow of the proverbial dyke.

Scotland is leading the rest of the home nations of the UK in this change. In England the "nones" represent 25% and in Wales 32%, with a low 6% in Northern Ireland.

But, in each country, there has been dramatic change in the past decade, with the proportion without religion rising by two-thirds. The pace of change is greater than anyone predicted in the 1980s and 1990s. This applies overseas too, where most European nations have witnessed a surge in declining religious adherence in the past 15 years.

In the United States, "nones" doubled between 1990 and 2012 to reach 20%. Only in Africa and parts of Asia has there been little discernible decline in religion.

The implications are great for culture, politics and social behaviour. Those without religion are the defining group in moral positions on sexuality and human rights issues. They are the ones taking the lead in the decline of church marriage and christenings.

Humanist celebrants have been making major inroads into this area in Scotland, and look likely to overtake the Church of Scotland within two years or so as the largest single provider of weddings outside registrar's offices.

While the majority of Scots are still, just, Christian with 54% of people declaring themselves thus, this is down from 65% in 2001. "Nones" are the only group showing significant growth.

It remains to be seen whether those without religion will also affect the independence vote in a year's time.

Will Tom Nairn's statement many years ago that "Scotland will be free when the last minister is strangled by the last copy of the Sunday Post" come true, or will the Kirk not matter either way?