Whether the recent upturn is due to demographic changes with immigration into the UK from Eastern Europe under EU free movement laws, or whether this represents a bottoming out of the decline remains to be seen. There are a number of demographic changes that may have contributed to the decline in religion as an institution in Britain, not least of which has been, until very recently, a general feeling of security as the baby boomers and especially their children were brought up in the welfare state created by the post-war Labour government in response to the Beveridge Plan. People were better housed, better fed, better clothed, better educated, better paid and had more leisure time and disposable income than at any time in history. In addition, they were brought up in a less deferential culture and were more inclined to examine the old assumptions and think for themselves rather than being prepared to think what they were told. And these ideas were able to spread more quickly because of the mass communication media.
Better education made us more willing to see the old religious fables and origin myths as just that, not science or a useful description of the Universe any more. Better security rendered us less susceptible to the false hope that religion offers and better communication made us realise we were not alone in these new attitudes and new-found scepticism. And of course better and more accessible contraception and better sex education has turned sex into a recreational activity carrying far less risk, especially for females, reverting sex to probably it's more natural role in human relationships and freeing it from stigma and guilt that religion had imposed on it.
The strongest predictor of whether a person grows up to be religious is whether their parents are... In terms of keeping people, the non-religious are doing very well indeed. It is extremely unusual for somebody brought up in a non-religious household to join a religion, but it is not at all unusual for somebody brought up with a religious affiliation to end up as non-religious... The very fact that there is such a group, that it is quite big and that there wasn't such a group before is an indicator of secularisation.
Stephen Bullivant, theologian, St Mary's University, UK. Co-editor of The Oxford Handbook of Atheism
Quoted in Losing our religion: Your guide to a godless future by Graham Lawton; New Scientist 30 April 2014
Now we have brought our children up to think for themselves, the biggest cause of religion - parental example - has been removed from half the population. Studies have shown that only about 3% of children with Atheist or non-believing parents are likely to become religious, whilst only 50% of children from actively religious parents are likely to follow them. In the UK, for every 10 people to leave Catholicism, only 1 joins.
Even for religious people, premarital sex will have been the norm in almost every case and most will have been living as a couple for some time. As the last chart shows, for all but the youngest age group, over 50% had cohabited prior to marriage, rising to over 80% for 30-45 year-olds, only a little below the cohabitation figures for civil marriages at 90%.
Religion has almost ceased to have any relevance to the institution or 'sanctity' of marriage in England and Wales and marriage is no longer seen as a prerequisite to a full sexual relationship.
ONS: Marriage Summary Statistics 2012 (Provisional) (Excel sheet 192Kb).
ONS: Marriage Statistics, Cohabitation and Cohort Analyses (Excel sheet 343Kb).
ONS: Facts About Marriage.