No one has explored this facet of human nature more exhaustively than the Italian sociologist Vilfredo Pareto:
As various religions succeed one another in history, their forms may be as different as one please, but after all they are all expressions of religious sentiments that vary but slightly. The modern free thinker enforces, in the name of Science, Holy of Holies, a morality but slightly differing from the code that the God of the Israelites proclaimed for His people, or the code that the Christians received from their God; or the codes that now one, now another, of the ancient peoples received from gods or from lawgivers legendary or divine….
Similar uniformities are observable even in phenomena much less important. In ancient times people who were sick made pilgrimages to the temples of Aesculapius in order to regain their health. They were succeeded in the Middle Ages by devout Christians who prayed to their saints for health and visited shrines and relics. Nowadays they would recognize descendants in the throngs that flock to Lourdes, in the devotees of “Christian Science”…
To such are still to be added the practices of those many medical quacks whom Daudet happily dubbed “deathers.” In their regard the credulity of the ancients has its perfect counterpart in the credulity of the moderns. At no time in history have quacks flourished more abundantly on the money of simpletons than they do today [circa 1905]; and in many countries the law protects such priests of the goddess “Science” just as religiously as it protected priests of the pagan gods of old—sometimes even more so. Believers gather in droves in those clinics and sanitoria which are temples of the modern quack. Some of them get well, if Mother Nature chances to look upon them with a kindly eye; but all of them contribute to the collection box of the high-priests of the goddess “Science” and their acolytes—among whom, let us not fail to count the pharmacists who sell their drugs at 1000 per cent profit; and the inventors of those patent medicines which shoot across the sky of publicity like meteors, cure every conceivable illness for more or less extensive, and often very brief, periods of time, and then are gone; not without leaving huge fortunes in the pockets of certain traders on public credulity who exploit the poor in spirit under the kindly eye of the legislator. And there is no argument, no fact, however obvious, however striking, that can avail to open the eyes of the fools. (1695, 1697)
With the improvements in medicine, the situation has somewhat improved in the hundred years since Pareto wrote. But it has hardly been a complete improvement. Quackery still survives in many forms, and is often resorted to as a last resort, when conventional medicine fails. Quackery, of course, is one of the more negative elements of religion. However, it is not as negative as Pareto paints it; science now recognizes the existence of placebo effects. Now in medicine, it is generally better to supplement placebo effects with conventional medical treatment, since science-based treatment is considerably more efficacious than placebo effects. But that is not true in all venues in life. There may be areas of life dealing with psychology of motivation or one’s general attitude toward existence which might be best served by the “placebo-like” comforts of religion.
In any case, whether religion is positive or negative in its overall impact on an individual or on society as a whole, the evidence strongly suggests that it is here to stay. Most human beings are incorrigibly religious. Even when they turn secular, their basic religious orientation remains. So why, then, should we waste our time quixotically inveighing against it? A far wiser policy for the statesman or the social leader is to try to cultivate the positive and discourage the negative elements in religion. Trying to argue people out of religion is a complete waste of time. Debates may be instructional or entertaining, but they’re not going to change many peoples’ minds.
Arguing people out of religion, far from being a good thing, may actually be a bad thing. What happens when people stop being religious? They become secular. Their religion simply takes another form; but it's usually a worse form. Centuries of trial and error have purged the religions of the civilized West (mainly Christianity and Judaism) of many of their worst excesses. The secular equivalents of religion, on the other hand, being rather new developments, have not undergone this sifting process. That is why various secular equivalents of religion may prove harmful while a religion such as conventional Christianity may prove, in its overall effects, beneficial.