Modern academic sociology began with the analysis of religion in Émile Durkheim's 1897 study of suicide rates among Catholic and Protestant populations, a foundational work of social research which served to distinguish sociology from other disciplines, such as psychology. The works of Karl Marx and Max Weber emphasized the relationship between religion and the economic or social structure of society. Contemporary debates have centered on issues such as secularization, civil religion, and the cohesiveness of religion in the context of globalization and multiculturalism. The contemporary sociology of religion may also encompass the sociology of irreligion (for instance, in the analysis of secular humanist belief systems).
Sociology of religion is distinguished from the philosophy of religion in that it does not set out to assess the validity of religious beliefs. The process of comparing multiple conflicting dogmas may require what Peter L. Berger has described as inherent "methodological atheism". Whereas the sociology of religion broadly differs from theology in assuming indifference to the supernatural, theorists tend to acknowledge socio-cultural reification of religious practice.
Classical, seminal sociological theorists of the late 19th and early 20th century such as Émile Durkheim, Max Weber, and Karl Marx were greatly interested in religion and its effects on society. Like those of Plato and Aristotle from ancient Greece, and Enlightenment philosophers from the 17th through 19th centuries, the ideas posited by these sociologists continue to be examined today. Durkheim, Marx, and Weber had very complex and developed theories about the nature and effects of religion. Of these, Durkheim and Weber are often more difficult to understand, especially in light of the lack of context and examples in their primary texts. Religion was considered to be an extremely important social variable in the work of all three.
According to Kevin J. Christiano et al., "Marx was the product of the Enlightenment, embracing its call to replace faith by reason and religion by science." But he "did not believe in science for science's sake … he believed that he was also advancing a theory that would … be a useful tool … effecting a revolutionary upheaval of the capitalist system in favor of socialism." As such, the crux of his arguments was that humans are best guided by reason. Religion, Marx held, was a significant hindrance to reason, inherently masking the truth and misguiding followers. As we will later see, Marx viewed alienation as the heart of social inequality. The antithesis to this alienation is freedom. Thus, to propagate freedom means to present individuals with the truth and give them a choice to accept or deny it. In this, "Marx never suggested that religion ought to be prohibited."
Central to Marx's theories was the oppressive economic situation in which he dwelt. With the rise of European industrialism, Marx and his colleague Friedrich Engels witnessed and responded to the growth of what he called "surplus value". Marx's view of capitalism saw rich capitalists getting richer and their workers getting poorer (the gap, the exploitation, was the "surplus value"). Not only were workers getting exploited, but in the process they were being further detached from the products they helped create. By simply selling their work for wages, "workers simultaneously lose connection with the object of labor and become objects themselves. Workers are devalued to the level of a commodity – a thing …" From this objectification comes alienation. The common worker is led to believe that he or she is a replaceable tool, and is alienated to the point of extreme discontent. Here, in Marx's eyes, religion enters. Capitalism utilizes our tendency towards religion as a tool or ideological state apparatus to justify this alienation. Christianity teaches that those who gather up riches and power in this life will almost certainly not be rewarded in the next ("it is harder for a rich man to enter the Kingdom of Heaven than it is for a camel to pass through the eye of a needle …") while those who suffer oppression and poverty in this life, while cultivating their spiritual wealth, will be rewarded in the Kingdom of God. Hence Marx's famous line – "religion is the opium of the people", as it soothes them and dulls their senses to the pain of oppression. Some scholars have recently noted that this is a contradictory (or dialectical) metaphor, referring to religion as both an expression of suffering and a protest against suffering.
Émile Durkheim placed himself in the positivist tradition, meaning that he thought of his study of society as dispassionate and scientific. He was deeply interested in the problem of what held complex modern societies together. Religion, he argued, was an expression of social cohesion.
In the fieldwork that led to his famous Elementary Forms of Religious Life, Durkheim, a secular Frenchman, looked at anthropological data of Indigenous Australians. His underlying interest was to understand the basic forms of religious life for all societies. In Elementary Forms, Durkheim argues that the totems the Aborigines venerate are actually expressions of their own conceptions of society itself. This is true not only for the Aborigines, he argues, but for all societies.