In the 16th century, after having been the Church of the western world for over 1,000 years, Catholicism faced a great crisis and challenge.
Several main religious groups, under individual leaders, split from the Roman Catholic Church over issues of reform and doctrine. This new branch of Christianity, called "Protestant," included Lutheranism, Calvinism, Anglicanism, Anabaptism, and Radical Protestantism.
The Church's Response
Sometimes called the "counter-reformation," this was a period of assessment and reform that had actually begun before the reformation.
The Council of Trent
Between 1545 and 1563, this council worked for church reform by:
Pope Pius V, Gregory XIII and Sixtus V helped put the Council's decrees into effect.
The Jesuits (Society of Jesus)
This educational and missionary society was founded in 1540 by St. Ignatius Loyola, it helped to revive Catholicism by establishing school systems and converting non-believers in new lands.