In the 16th and 17th centuries, the name of Huguenots came to apply to members of the Protestant Reformed Church of France.
Huguenot predecessors included the pro-reform and Gallican Catholics, like Jacques Lefevre. Later, Huguenots followed the Lutheran movement, and finally, Calvinism. They shared John Calvin's fierce reformation beliefs which decried the priesthood, sacraments and doctrines of the Catholic Church. They believed in salvation as an act of God as much as in creation as an act of God, and thus that only God's predestined mercy toward the elect made them fit for salvation. Some see this dual emphasis on creation and on salvation, and God's sovereignty over both, as a cornerstone principle for Huguenot developments in architecture, textiles and other merchandise.
Above all, Huguenots became known for their fiery criticisms of worship as performed in the Roman Catholic Church. They believed the ritual, images, saints, pilgrimages, prayers, and hierarchy of the Catholic Church did not help anyone toward redemption. They saw the Christian faith as something to live out in a strict and godly life, in obedience to biblical laws, out of gratitude for God's mercy – not as performing rituals and as obsession with death and the dead. As other Protestants also believed at the time, they thought that the Roman church needed radical cleansing of its impurities, and that the pope represented a worldly kingdom which sat in mocking tyranny over the things of God, and was ultimately doomed. Rhetoric like this became more fierce as events unfolded, and stirred up the hostility of the Catholic establishment.
Huguenots faced periodic persecution from the outset of the Reformation; but Francis I (reigned 1515 – 1547) initially protected them from Parlementary measures designed for their extermination. The Affair of the Placards of 1534, changed the king's posture toward them: he stepped away from restraining persecution of the movement . Still, Huguenot numbers grew rapidly between 1555 and 1562, chiefly amongst the nobles and city-dwellers. During this time their opponents first dubbed the Protestants Huguenots; but they called themselves reformés, "Reformed". They organized their first national synod in 1558, in Paris. By 1562 they had a total membership estimated at at least a million, especially numerous in the south and central parts of the country. The Huguenots in France never numbered more than just over two million, compared to approximately sixteen million Catholics during the same period.
Violently opposed to the Catholic Church, the Huguenots attacked images, monasticism, and church buildings. Most of the cities in which the Huguenots gained a hold saw iconoclast attacks, in which altars and images in churches, and sometimes the buildings themselves were torn apart. Bourges, Montauban and Orleans suffered particularly.