The Wikipedia article on the French Wars of Religion says that the Calvinist form of Protestantism, in particular, spread into the nobility. Now, I'd like to know why is that, and not Lutheranism for example?
I speculate that Calvin is closer to Zwingli in the issue of the limits of authority of the king, but it could also be for more trivial reasons (e.g. language barrier of Lutheranism).
Opposition to the monarchy was indeed a major factor.
Many French nobles, a majority of whom adopted Calvinist doctrine, sought to regain and extend privileges lost to the monarchy.
- Nexon, Daniel H. The Struggle for Power in Early Modern Europe: Religious Conflict, Dynastic Empires, and International Change. Princeton University Press, 2009.
Calvinism represented opposition to the absolutism. It therefore naturally appealed to the political sensibilities of the French nobility vis-à-vis the monarchy. This led to many of them eagerly adopting Calvinist doctrines.
Everywhere, whether in England or Scotland, Holland or France, Calvinism fights for political liberty, or at least ranks with the forces that war against absolutism. The popularity of Calvinism among the French nobles is partly to be accounted for by this characteristic. They renewed under cover of religion that struggle against the monarchy in which they had been defeated when they fought on purely secular grounds.
- Grant, Arthur James. The French Monarchy (1483-1789). Vol. 3. The Cambridge University Press, 1914.
In contrast, Lutheranism was politically mild and thus found no resonance with the French nobility or urban elites who embraced Calvinism.
Additionally, the patronage system of France's provincial nobility helped Calvinism spread rapidly. John Calvin, well aware of how the system works, targeted important aristocrats. He constructed a successful strategy based on the hopes that converting one influential man would lead to the mass conversion of his clients and relatives.
Calvin appreciated the impact of clientage on religious conversions. He attached great importance to winning over the nobility to his cause, knowing that the conversion of a single nobleman could lead to multiple conversions among his relative and dependents.
- Knecht, Robert Jean. The French Wars of Religion 1559-1598. Routledge, 2014.
Lastly, there has also been an argument based on economics:
The relatively sudden conversion of so many nobles to the Calvinist faith has been explained on economic grounds. The nobles, it has been suggested, were particularly hard hit by the steady rise in prices ... Finding themselves impoverished, the nobles attache themselves to the cause that seemed most likely to bring them easy profits. Calvinism offered scope for material gain at the expense of the Church.
- Knecht, Robert Jean. The French Wars of Religion 1559-1598. Routledge, 2014.
For example,
Families holding bishoprics struggled to maintain their income and to defend their ecclesiastical properties from Huguenot seizures during the sixteenth-century religious wars. Calvinists frequently occupied and redistributed Catholic church lands and properties in Languedoc and Guyenne.
- Sandberg, Brian. Warrior Pursuits: Noble Culture and Civil Conflict in Early Modern France. Vol. 128. JHU Press, 2010.
However, Professor Knecht rejected this explanation by arguing that the French nobility did not experience a general economic collapse. I include it only for reference.
Religious sects (heresies) tend to be very heavily correlated to societies and their desires for who they want to associate with, and distance themselves from. For instance, German tribes in the late Roman period tended to take up Arianism, which quite conveniently provided them independence from Roman popes and a common sect amongst themselves. A similar phenomenon happened with Shi'ism vs. the Sunni amongst the Indo-European Iranians.
John Calvin was a Frenchman, and thus Calvinism was essentially France's home-grown protestant theology. This was a time where France had a century prior been the most powerful state in Europe. However, Spain's newfound wealth and power had recently reduced France to an arguable #2. This contributed to France having recently lost control of the Papacy.
So in a way you could view the whole episode as a proxy war over whether France should continue to try influence the papacy, or go its own way. Joining a reform movement that they weren't the senior member of would not have furthered the latter goal, and they couldn't guarantee political control of an externally-based sect. Thus Calvinism was really the only other feasible religious option.
This question can be subdivided into two more:
1) Why Protestantism (Calvinism and Lutheranism) vs. Catholicism and 2) Why Calvinism vs. Lutheranism.
1) For Protestantism over Catholicism. Protestant theology held that Christians were connected to God through the scriptures, rather than through the Church. This came at a time when the (Catholic) church came under heavy suspicion for corrupt practices such as the sale of indulgences. The basic theory was that the "people" had the right to circumvent, and otherwise circumscribe the hierarchy of the Catholic church, (and by implication, secular rulers such as king and queens). This process would cut out the expensive "middlemen," and was highly appealing to subscribers to the so-called "Protestant Ethic."
2) Why Calvinism over Lutheranism:
Upper class people were often drawn to Calvinism over Lutheranism, because while both doctrines preached the "election" of Christians by God, Lutheranism put a greater emphasis on faith, while Calvinism preached salvation by "predestination", or God's choice. Under Calvinism, earthly riches and prosperity were a "mark" of God's "choice," a doctrine very appealing to some upper class Protestants such as French nobles (and prosperous Dutch merchants).
Calvinism found its rawest form in South Africa, where "Dutch" (including German and French) settlers made it the basis of "apartheid," because of the "obvious" superiority of those settlers over "native" Africans. The Calvinist ethic can be best described by a take-off on the line from "Animal Farm": "All Protestants are equal, but some Protestants are more equal than others."
One issue was that Calvin was French, and that may have explained part of the popularity of his doctrines in France, while Luther was German, which may help explain why German nobles tended to follow him.
