The Medieval Church was marked by numerous reform movements, sometimes accepted by the authorities (the reforms of Gregory VII and Francis of Assisi, for example), sometimes declared heretical (Vaudois, Cathares). In the 16th century a new wave of religious disputes, driven by progress in printing methods, led to the division of the Church (or schism). This movement is called the Reformation and ended up in the birth of the Christian Protestant churches.

The Reformation was launched in 1517 in Germany when the German monk Luther published his 95 theses denouncing the principle of indulgences. It rapidly took hold in Scandinavia, the Netherlands and Switzerland, where it was given momentum by the French theologian Jean Calvin. The Reformation also penetrated France (where its followers were called Huguenots). There it was violently confronted by the Catholic powers, as it was in the Netherlands and in Germany. Europe was soon aflame with the ‘Wars of Religion’ (in the second half of the 16th century).

The Catholic Reform (formerly known as the Counter-Reformation, a term judged by historians as being too reductive) is a movement which took form at the heart of the Roman Catholic Church in the 16th century with the aim of limiting the expansion of Protestantism and also trying to reform a Catholic Church which had lost direction. The birth of reforming religious orders, such as the Society of Jesus or the Oratorians), as well as debates around doctrinal and disciplinary questions during the Council of Trent (1545-1563) permitted the emergence of a clergy which was better educated, better trained and more capable of carrying out its pastoral duties effectively.