We often see the Greece of Antiquity presented as the pillar of rational thought, but philosopher Bertrand Russell reminds in his magnificent 'History of Western Philosophy' that Greece was also home of many important quite irrational cults and mysteries. Rational thought had to fight for breathing space with the believers of supernatural and mystical even in Greece. This fight for supremacy between the rational side and the mystical side of human nature has of course being going on in all societies at all times, but the big thing was that in Greece rational though at last had the upper hand at times or at least it was well respected and allowed to flourish.
When Christianity took over in Europe, the mystical and supernatural got a definite upper hand. The big difference was that Christianity did not respect the rational side of humans and the rational way of thinking was largely suppressed for a long time. Of course, there were thinkers who tried to make Christianity more rational, as the more rationally inclined people did not disappear even during the heyday of Christianity in the medieval times. They just had to adjust themselves, but they also tried to change Christianity to suit also their own needs, for which it was sorely ill equipped.
However, as the mystical side of humanity had a clear and unchallenged supremacy in the early medieval times, the majority of the naturally more rationally inclined part of the population just had to bide their time. The new resurgence of rationality was, however, luckily not far away, as Renaissance and most of all the Age of Enlightenment were just signs of the return of rationality to societies. In the end rationality got the upper hand again in Western Europe. The modern western nations can well now be described as societies that are based on the central ideas of rationality
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All this does not mean that I would not think that rational, secular humanism is the best medicine formany of the biggest ills of humanity. I just think that the irrational, mystical side of humanity needs to be allowed to be find expressions also, if we want to stable societies. I'm saying that even though I do think that rational humanism is the overwhelmingly superior answer; but I think it can never be the only or absolute truth. If I would ever make a claim like that, I would not be any better than those who believe in the 'absolute truths' so eagerly still offered by the religions.
http://beinghuman.blogs.fi/2010/07/25/is-rational-humanism-the-only-possible-answer-to-the-ills-of-humanity-9037446/