The reordering of religion and the sundering of the social unity that it had once provided to European culture was the most significant development of the sixteenth century. It is impossible to understand the time without taking a look at this. Religion was not a matter of personal preference or opinion; it was the very basis of society.
The Pre-Reform: Society Awakens
The rediscovery of the learning of the ancient world, the printing press, and all the other forces that came together to create the Renaissance also affected the Church. At the end of the fifteenth century and the beginning of the sixteenth, Christian humanists sought to apply the new style of scholarship to the study of scriptures in their original languages and to return to the first principles of their religion. In the interests of spreading religious understanding, they began to translate the Bible into the vernacular languages. The end of the fifteenth century saw a popular spiritual revival of a more mystical nature as well. The Renaissance belief in the "perfectibility of man" made people less content with things as they were, and more interested in improving them in the here and now.
Corruption of the Church
No one could argue that the church was not corrupt: holding vast wealth, exercising enormous political power and waging war, it was administered by holders of patronage positions that had more interest in lining their pockets than in promoting the welfare of their "flocks". The Christian humanists criticized these all-too-human failings, while striving for a purer church.
Martin Luther
In 1517, a dispute about who was entitled to a cut of the revenues generated by papal indulgence sellers provoked the controversy that led the Augustinian monk, Martin Luther, to nail his 95 theses to the church door at Wittenberg. The upshot of Luther's theses was that Christians are saved by faith, and faith alone, and that no amount of works (including the purchase of indulgences) made any difference at all. The Pope, Leo X, was a fairly easy going fellow, not inclined to vigorously prosecute this first appearance of heresy and he thought it could be worked out diplomatically.
As it turns out, it could not. Luther was not immediately burnt for a heretic; he was allowed to present his case in court and had a powerful effect on the populace. He also had a powerful patron and protector in the Elector of Saxony, who shielded him from the ecclesiastical authorities. In addition, the media explosion brought on by the printing press spread his message much further than it otherwise might have gone, and made him the focus for all sorts of religious, spiritual, political, and economic discontent. The right to read and interpret scripture lead to the throwing off of the chains of papal and ecclesiastical authority; and taking this to mean political and economic freedom as well, there were widespread revolts among the German peasantry. This horrified Luther and many of the civil powers.
It was not the desire of the intellectual reformers to challenge civil authority, but it was a consequence.
The Council of Trent
Eventually the church mobilized itself to deal with splintering of its authority and held the Council of Trent. It was the purpose of this council to try to define a common ground of belief and practice for all Christians, and to attempt to heal the schism. It opened in 1545 and met for 18 years, during which it healed nothing.
The Counter-Reformation
The Council of Trent did try to address some of the abuses of the church, calling for a more effective, educated, and involved clergy.
The Protestants
Protestantism in France had more appeal in the towns than in the countryside. In the towns, artisans and learned professionals made up a disproportionate number of the Huguenots (when and why this term was coined for French Protestants is unknown). They were overwhelmingly more literate than the general population, which was important for a religion that so strongly emphasized bible study. Members of new trades like printing and bookselling, as well as newly prestigious trades like painting and gold-smithing, and new manufacturing technologies like silk-making were more likely to take to Protestantism than members of older, more tradition-bound trades. As a whole, these were artisans with more education, independence, and entrepreneurial spirit than average.
French Protestantism would never have amounted to the potent social force it became if it had remained a religion of artisans. In the 1550s and 1560s, large numbers of noble elites were attracted to it. Very often, these decision-makers were reached through the influence of their mothers and wives.