Is Religion the "opiate of the masses"?
Most certainly not. Rather, it is the best indicator of underdevelopment. Correlations done between levels of religious affinity and economic development (GDP), tend to show a downward trend. That is to say, as an economy becomes more 'developed', the "religiosity" of a population tends to decline--a relationship sophisticated religious advocates seem to be very aware of. Neil Postman, a Catholic cleric if I remember correctly, seems to be aware of this relationship by his interesting critiques on technology. He notes that there is little religion in technologically sophisticated societies--another concept perhaps for 'development'--and hence proceeds to consistently 'attack' technology in his body of literature in order to 'defend' religion. We might even suggest that the hatred many islamic scholars have of science and technology are also related to their vague awareness of this relationship, but which tends to be associated with 'westernization' and hence incorrectly defined as the imposition of a 'cultural model'. Economic development, which all nations and individuals desire as a general rule, will ultimately have a profound impact on its religious structure over the long run.
One might speculate as to why the relationship actually exists, as there would seem to be no direct relationship between the two. After all, why should the beliefs pertaining to one's preferred 'deity' have any relationship whatsoever as to how 'wealthy' one is? It appears that there is more to social psychology than meets the eye. In other words, a demand that is always present--the human minds needing to make sense of the world--tends to be fulfilled differently, according to economic structure of a society. Societies with few resources are unable to meet this demand as effectively given their limited resources, and hence religion becomes the most efficient manner in which to supply this need. Reading the respective 'book of knowledge' (bible, koran, etc) in particular societies will thusly fill the void by supplying both descriptive and prescriptive knowledge of the world. This is both a result of affluence as well as supply. However, more affluent societies provide individuals with simply better conceptual tools (i.e. science, social science) as well as (generally speaking) more time. A flourishing book industry--or the internet--might be cause and consequence of secularization, fitting the dynamics described with regard to the medieval/renaissance period.
The odd exception to the gnp-religiosity inverse correlation is the United States, which would surely be used by many to dismiss the correlation as a casual one with no substantive value. The US has both a high gdp and a high religiosity index. However, if we are to accept the general rule, we might actually be led to a conclusion that is not immediatley obvious in the previous 'theory framing', but one that would be more widely accepted. In other words, the exception in the case of the US is not necessarily a violation of rule with regard to its causal link (religion-economy) but rather might actually be shedding a great deal of light on the actual 'de-modernization' processes that the US is undergoing right now. The high religiosity might actually be an indication that 'all is not well' in that nation, a problem which economic figures as GDP/GNP do not seem to be fully revealing at the present moment. (The actual structure of production of that capital is hidden in its economic analysis.) However, the decline of the dollar and industrial flight would suggest other wise.
If we in fact accept this view (inverse economy-religion correlation), we might be led to the logical conclusion that the Catholic Pope's current visit to the United States will actually be extremely favorable to that particular religion by boosting its members in that nation. If our interpretation is correct, the decline of economic development has already created a type of a demand for the 'religious mentality', and hence a correspondent increase in US catholicism. However, there would be a grave irony in this view, if we abide by Catholicism's internal values. If the religion is meant to assist the poor, would its increase be actually perpetuating their condition--and hence a contradiction between its alleged social goals and its actual social function? Would the intention to assist actually end up doing more harm than benefit? Difficult to say, although our correlation would seem to suggest that in fact it would increase poverty.
We might also note the contradictory irony that religion might in fact seem to be an 'opiate of the masses' (contrary to our initial statement), but it does appear that this marxist claim is too charged with value-judgment to do justice to the situation. That is to say, it might represent a smaller case of a much broader phenomena pertaining to more complex issues of 'national economic development' and the world system of which these national economies are a part of.
Here we enter into that extremely complex world of cause and effect; how exactly are the religious and economic mentalities/structures associated? It seems like it is a most opportune moment to reopen the Weberian paradigm and take Catholicism as a case study.
(We might also note that the 'attack on technology' as a result of this perceived relationship is a mistake in that it is not actually seeking to understand the phenomenon involved, and hence 'unfaithful' to its claim in being a social science. They avoid a critical scrutiny as to the nature of religion and actual social processes. If we accept the view that Islam is a body of beliefs appropriate to older bedouin lifestyles of the desert, the same thing might be said of catholicism, which might be characterized as a 'cultural residue' of a socioeconomic structure very different from our own. In order to preserve a cherished set of values, a political institution is set up which acts as a contra-cyclical force in order to shift the tendency backward to its original state. This is not to say that religions cannot accomplish this said goal, as the case of China seems to suggest; whether they should or not, is another matter altogether.)