Decline in attendance at religious worship is a characteristic of a number of religions. The single most common reason given is perceived irrelevance to the life and problems faced by the individual. Other reasons include a feeling of being unwelcome and dislike of the leadership within the religion.
A survey of eight countries found that 54% of Americans visit churches, mosques, synagogues, temples, etc. at least once a month, 45% of Italians, 39% of Austrians, 28% of Dutch, 20% of British and 7% of Hungarians. So few people are entering the clergy that the average age of priests is now close to 60.
In the UK in 1995 it was reported that overall some 14% claim church membership, although this figure is higher in Scotland and Wales than in England and six times higher in Northern Ireland. 8 million people went to church regularly in 1975 but that this had fallen to 6.7 million in 1992; a further fall of a million was predicted by 2000. The report showed that the Church of England had lost 21% of its worshippers in that period, Roman Catholics lost 19%, Methodists 23%, and Presbyterians 24%. It was expected that the Church of England alone would lose 300,000 members and close nearly 600 churches by the year 2005. Despite this, nominal allegiance to the Church of England is high; almost half of the English claim to be Anglicans. As one sociologist put it, it is the Church from which most people choose to stay away.
The fact that few people go to church regularly shows that religious leaders are failing in their central task to answer the spiritual needs of people. They are looking to fulfill the need for meaning from sects, cults, disciplines, therapies etc.
The traditional picture is that people stopped believing and then stopped going to church. In fact the opposite is true. People stopped going to church, and belief faded. Activities which once brought people within the ambit of the church have been taken away form it. The result was that the churches no longer played a central role in people's everyday lives. You can think of faith as a package or you can think of it as a faithful exploration within a tradition. Our style of thinking today tends towards the latter. It is the lack of a highly organized and clearly defined faith that we suffer from today.
The decline of organized religion is due in large measure to the general erosion of authority and decline in respect for institutions. People suffer spiritual longing because modernity has not supplied them with the answers they crave. But because they reject any imposed authority, they believe they can find the answers within themselves. So we have got a supermarket spirituality in which people shop around for beliefs that make God in their own image.
Although church attendance is declining across Europe, increasing numbers of people are undertaking pilgrimages and visiting shrines such as the tomb of Saint James (Santiago de Compostela) or Lourdes. Some shrines report that attendance is twice that of a decade ago. These trends are seen as a search for more direct spiritual roots than have been accessible through formal religious practices. Church membership and attendance is increasing amongst evangelical groups as the Pentecostalists. An Islamic revival from the 1980s has ensured numerous conversions to Islam or to Sufism, partly in reaction to the crass materialism of Western civilization.
The size of congregations is meaningless. Surveys produce contradictory data. There's evidence that about half of all adults in Britain say they have had some kind of religious experience, but we simply don't know what that means.