Prior to the Neolithic revolution, it is believed that traditional hunter-gatherer societies had proto-religions whereby animals, plants, rocks, the wind, the moon, the sun were all seen as having a spirit-aspect. It was in the nature of such societies that they were small kinship groups managed by a charismatic leader: the social function of such religions was really ‘magical environmental management'.
The advent of the Neolithic revolution in both its farming and herding aspects introduced the problems of scale. Populations rapidly grew beyond the scope of traditional, organic leadership where the leader was able to know everyone. This required the codification of law, ritual and morality. But how to make such impersonal social rules stick?
Make them the dictate of a supernatural super-chieftain, with an earthly bureaucracy-priesthood as enforcers. Thus the pastoral civilizations of the Middle-East created the Abrahamic religions (‘The Lord is my shepherd') while the more settled farming communities of South and East Asia produced the rigidities of Hinduism and Confucianism. Even Asian egalitarian reactions such as philosophical Taoism and Buddhism soon became encrusted with the priesthood-bureaucracy and attendant rituals.
This says something important about the role of religion as a necessary and effective social glue. In the unequal societies of feudalism (and Asian variants) such glue was all-important and came with real and bloody social sanctions. Latterly with capitalism, with its dissolution of traditional social relationships and increasing living standards, the social glue aspect has come to seem less important (the United States with its ethnic diversity and individualistic ethos as usual being the exception).
It is relatively easy, Dawkins-style, to prove the absurdity of a supernatural agency, given the lack of any direct evidence and the inconsistencies of the revealed sources. The decline of a religiously-based code of acceptable conduct is harder to manage. At the bottom of an atomised, depersonalised civil society tribal 'gangs' spring up, defining everyone else as 'other'. Who wants to live where 'everything is permitted'*?
Life under the yoke of a ‘monopolistic’ authoritarian religion can be pretty benighted and oppressive. Life in the absence of common standards of decency is pretty nasty. Perhaps we need diversity, competition, a market in religions?
Er, isn’t this pretty much what we have in the US today?
Well, maybe with more regulation then!
And did you mean just for the underclass?
* cf. "The Brothers Karamazov" by Dostoevsky.