Why was Catharism which came more than 3 centuries before Protestantism not as succesful as the latter? If I recal correctly Catharism was reasonably widely spread it formed mostly around rich harbor towns (?) like Protestantism (?). What are the main differences between the two? Oh and I would also like to know which social groups where mostly likely to be atracted to the 'heretic' religions?
Hi! You might be interested in this similar thread:
Well, I think the most important post on this topic is the ones by /u/idjet who explains that there is actually little evidence that the Cathars even existed.
I think your question misunderstands the nature of both Catharism and Protestantism. Not only are there the problems with the existence of Catharism that /u/idjet relates, Protestantism was not originally perceived as a heresy. It was a protest against the abuses of the Roman hierarchy, and a call to reform, not a heresy agaisnt the doctrines of Christianity as it was observed in the West. What is, to me, more interesting is that the protestant reform movement was successfully outright rejected by the Church majority, forcing both sides into a schism, when previous reform movements such as the Cluniacs and Franciscans were absorbed into, and helped to strengthen the Western Church.
In the European west of the high and late middle ages, no heterodox form of Christianity stood a chance of success in the face of the alignment of power of Catholic secular and ecclesiastical institutions and law. Whether it be one-off 'heretics' like the raging independent Henry of Lausanne in the 12^th century, or the Waldensians that grew out of the movement Peter Valdes (Waldo) started in late 12^th century, whether it be the spiritual Franciscans or the various forms of Beguines or the Free Spirits of the 13^th and 14^th century, none could survive the enforcement of Catholic orthodoxy through either the Church's aggressive preaching and prosecution (the medieval inquisition, et al) or through the secular support and enforcement of the same. To be heterodox was not just a religious matter but effectively became a secular crime.
Nor could what one historian usefully called the 'debris of pre-Gregorian forms of Christian worship' survive the rooting out and persecution, and this includes the varieties of worship wrongfully collected under the term 'Cathars' and those 14^th and 15^th century targets, witchcraft and devil worship.
Now, as for the question of 'which social groups were most likely to be attracted to the 'heretic' religions', this is a problem that historians have tried to solve for centuries, and the Roman Church tried to solve itself in the middle ages. A sociology is, frankly, impossible for one single reason: the definition of a 'heresy' is entirely contingent and changeable depending on the prevailing definition of orthodoxy at the moment. So, for example, in 1179 at the Third Lateran Council Waldensianism was normalized in relation to Roman Catholicism and officially considered orthodox; within two years Valdes was excommunicated by the same papacy for not following certain 'rules' set down, chief among them that Valdes must follow instruction of the Bishop for whatever diocese they happened to be preaching in; the followers of Valdes were suddenly found themselves considered 'heretics'.
Time and again we see that heresy in the middle ages was not simply a matter of one making a deliberate choice from a smorgasbord of religions. Yes, at times some followers chose to align themselves or believe in a heterodox Christianity with deliberateness, the spiritual Franciscans, Beguines, Waldensians in the following century would qualify as deliberate dissenters, or in the Church's view as willful heresy. But, at the same time, and this follows for those regions in the 13^th century which we call Cathar, the poor infrastructure and assiduousness of the Church (for whatever reasons) just did not cohere the beliefs of the population - which lead to great heterodoxy in the practice of Christianity (but not necessarily the core beliefs). Chief testimony to this are the fairly voluminous inquisition records from the 13^th and 14^th century which tell not of an organized, heretical counter-church, but of a diversity of practices at a low-level; this would include not observing certain sacraments, not attending church on required days, minor infractions of theology, and the like. I would suggest in fact that many of the 'violations' which inquisitors turned up could in fact be found across Europe at the same time, but it is only because inquisitions gained a foothold in southern France that we know of it.
The links in other comments in this thread speak to the power which permitted Protestantism (the Reformation) to flourish; by the same token power was the reason Catholic orthodoxy was the law of the land for centuries after the Fourth Lateran Council of 1215 and made effective development of wide-spread, uniform heterodox beliefs impossible.