Nonetheless, since (and to some extent before) the Enlightenment, there have been those expecting human society would come to its senses and realize there is no God and, thus, that religion is superfluous in the modern world. The views of various leading thinkers have added impetus to this opinion, including Voltaire, David Hume, John Stuart Mill, and, of course, Charles Darwin. Within the sociological tradition, the secularist figure who led the way was Auguste Comte, whose evolutionary theory postulated that religious ways of understanding natural processes were inevitably yielding to a scientific world view. Interestingly, he was responsible for the founding of the Positivist Church, which still has a following in Brazil.

From the second half of the nineteenth century through to the 1960s, the sociology of religion was predominantly concerned with charting the progress of secularization. The general assumption was that processes such as industrialization, urbanization, rationalization, bureaucratization, and modernization were responsible for a gradual erosion of religious beliefs and practices. Then, in Eastern Europe, China, and other communist states, there was the introduction of state-imposed secularism. One way or another, an apparently irreversible process of secularization seemed to be removing religion from the structure and culture of society.

One of the best-known and most influential of contemporary sociologists advocating the secularization thesis was Bryan Wilson, who, in his seminal study, Religion and the Secular State (1966), defined secularization as "a process whereby religious thinking, practice and institutions lose social significance."

In politics, education, welfare, health, and the economy, rational and/or profit-making motives, rather than religious values, were increasingly employed; the state or private enterprise, rather than the Church, determined how the basic functions of society would be fulfilled. But this, Wilson stressed, did not mean that religion would disappear altogether. It could still be practiced at the individual level as a private, leisure pursuit.

Towards the end of the 1960s, the "secularization debate" started to heat up as a growing number of sociologists and other scholars began to question the theory - with one (David Martin) going so far as to recommend that the concept should be eliminated altogether. Many of these critics, though not all, came from the United States, where the obvious indices of religiosity (church membership and attendance or public rhetoric) provided less support for inevitable secularization than in Europe.

But from any perspective it was becoming increasingly obvious the concept of secularization was an all-too-blunt instrument for analyzing the processes that had been occurring in the West, let alone when looking at the religious scene from a global perspective. Differences between the North and South Americas and the Western and Eastern Europes were undoubtedly considerable, but these paled into insignificance when compared to the vastly differing situations in India, Africa, Asia, or the Middle East.

American sociologists such as Charles Glock and Rodney Stark separated religion into different dimensions (belief, ritual, experience, and knowledge), while Belgian Karel Dobbelaere pointed out that secularization may refer to relatively independent dimensions (societal systems; religious organizations; individual religious involvement). Today it is clear that the messiness of actual relationships between religiosity and secularity demands much more detailed empirical analysis and the development of much more sophisticated conceptual tools.

There has been globalization from the time of the silk trade and before, but the extent to which it affects our daily lives today is unparalleled in history. Just as industrialization and modernization changed the social and cultural situation within which religious life had been experienced in the 19th century, so the social environment has radically changed with contemporary globalization. Increasing geographical and social mobility and the expansion of the mass media have challenged old ways and offered an unprecedented variety of new ways of looking at the world.

So it is not altogether surprising the changes taking place on the religious front have led some to insist that religion is not dying but undergoing a radical transition. There is, however, a twist to the fact that the supermarket of religious options is so well stocked and widely accessible. The sociologist Peter Berger, once a strong believer in secularization theory, has suggested that the challenge to religion today is no longer secularization, but pluralism.

Religious pluralism also has existed since time immemorial, but until relatively recently it tended to exist along ethnic or cultural lines. It was a group thing. Today it is increasingly the result of individual decisions. The very fact that so many different ideas can be encountered - in the school or in the workplace as a result of immigration, in the sitting-room by way of satellite television, or through the worldwide web - means truths once unquestioningly taken for granted now have to be justified.

As a result, such truths may be abandoned, or they may be adhered to with a far stronger tenacity than was necessary when there were no alternatives on offer. And, indeed, there is a movement from traditional religious beliefs and practices to a variety of both secular and religious alternatives.

Britain provides an interesting example of the apparent contradictions and paradoxes. Although both England and Scotland have their own established churches, it is arguable that religion plays a considerably less obtrusive role in public life than in the United States. In the 2001 national census, 72 percent of the UK population said they were Christians; 5 per cent belonged to non-Christian religions (including 390,000 "Jedi"); 16 percent said they had no religion; 7 percent declined to respond. According to this, one might assume four out of five Britons were "religious."

However, 40 per cent never attend a place of worship, and only one in 10 does so weekly. Even more curiously, in a national survey I conducted in 1999, only 26 percent of Britons said they were members of a religion, yet there were 29 percent who said they felt they belonged. When asked if, whether or not they attended church, they considered themselves religious, a third answered positively, two fifths negatively, a fifth were uncertain, but 13 percent, while not considering themselves religious, did consider they had some sort of a spiritual life. Although it is unclear precisely what they meant by spiritual, it would be a mistake to assume such people were unambiguously secular.

Age has long been recognized as one of the most significant variables associated with the decline in traditional religion, but an examination of longitudinal studies by the English demographer David Voas reveals that most British adults do not change their religious beliefs or practices once they reach 20. According to Voas, it is the social environment in which children are raised that has changed, resulting in each generation being less religious than the one before.

While two non-religious parents successfully transmit their lack of religion to their children, two religious parents have only a 50/50 chance of passing on their faith, and if just one parent is religious there is only a one in four chance of children following in that parent's faith. In all cases, however, eight percent of the children will take up a religion that differs from that of both parents. The "new" religion may be one of the weakening traditional religions, or it may be one of the new, immigrant or revivalist forms of religiosity and spirituality that are to be found spreading across the world - including an assortment of fundamentalist groups.

Religious fundamentalism as a concept has been extended far beyond its initial reference to conservative American Protestants. Now it frequently entails considerable political baggage as a direct or indirect reaction to secularism. In their major University of Chicago study of the early 1990s, Martin Marty and Scott Appleby identify fundamentalism with both orthodoxy and orthopraxis (correct religious behavior) as "a process of selective retrieval, embellishment, and construction of "essentials" or "fundamentals" of a religious tradition for the purpose of halting the erosion of traditional society and fighting back against the encroachment of secular modernity."

Several of the thousands of tiny new religions that have mushroomed around the globe over the past half-century embrace some fundamentalist claims, but many do not. Indeed, it is impossible to overstate the enormous variety of ways in which the movements address the questions of ultimate concern traditionally answered by the mainstream faiths.

Some, like the Raelians, deny they are religious, while others, like Scientologists, have fought in the courts for Scientology to be classified as a religion. Clearly distanced from traditional religious institutions (and sometimes dismissed as secular by those who employ traditional indices of religiosity) are Paganism, Wicca, New Age, and Human Potential movements, and what has been termed "the new spirituality."

In some ways reflecting the span of new types of religiosity, the secularisms of contemporary society show a comparable diversity. Most stridently, there are what might be termed the fundamentalist "religious atheists," who may be humanists or hard-line communists but adamantly insist there is no God. Then there are the agnostics who take the position that, as there is no way of knowing whether or not there is a God, there is no point in spending time worrying about religious issues.

Perhaps most secular of all are those who just do not bother to think about religion or religious questions in their everyday lives. Religion is totally irrelevant to their interests, be these their work, their family, or the Manchester United soccer team. But there are also "apathetic secularists," who might equally be called apathetic religionists. For them there may or may not be a God, but they expect religious institutions to be there to perform certain regular functions, such as rites of passage, or to turn to at times of national or personal crisis.

Of course, none of these "types" is more than a caricature. Few human beings are consistent in their beliefs. The most devout can have moments of doubt - as, perhaps, can all but the most faithful of secularists. It is clear, however, that an increasing number of options are available for generations who find their parents' religious faith and practice inadequate for or irrelevant to their own lives.