The election of Joseph Ratzinger as Pope Benedict XVI in 2005 gave the world a Bishop of Rome coherent with, but significantly different from, his predecessor. Pope John Paul II and Cardinal Ratzinger were close colleagues in the Vatican for many years. As head of the Congregation for the Doctrine of the Faith, Ratzinger was point man on several important doctrinal disputes that historians will consider crucial to John Paul’s papacy—liberation theology, faith and reason, and reproductive morality in particular. Ratzinger was primarily responsible for the Catholic Catechism. The two functioned almost as one mind.