He was the youngest of three children in a family of modest means. He spent his youth in Trauenstein, where he studied theology, becoming a priest in 1951.
Ratzinger's 1953 dissertation was entitled "The People and the House of God in Augustine's Doctrine of the Church", while a dissertation on Bonaventure qualified him for a professorship. He taught dogmatic and fundamental theology from 1952 to 1959 at a college in Freising, in Bonn between 1959 and 1963, in Muenster between 1963 and 1966, and in Tuebingen between 1966 and 1969.
Ratzinger became a professor of dogmatic theory and dogma history in 1969 at the University of Regensburg, where he was also vice-rector. From the beginning of the Second Vatican Council in 1962, he was a theological consultant to Cardinal Joseph Frings, the Archbishop of Cologne.
Pope Paul VI appointed him Archbishop of Munich on 27 March 1977 and Cardinal on 27 June 1977.
He was Relator of the 5th General Assembly of the Synod of Bishops (1980) on the theme "Mission of the Christian Family in the Modern World", while in 1983 he was President Delegate to the 6th Synodal Assembly on the topic "Penitence and Reconciliation in the Mission of the Church".
On 25 November 1981, Pope John Paul II named Ratzinger Prefect of the Sacred Congregation for the Doctrine of the Faith, president of the Pontifical Biblical Commission and president of the International Theological Commission, offices he held until John Paul II's death.
Between 1986 and 1992, Ratzinger was president of the Commission for the Catechism of the Catholic Church and the catechism was made under his leadership.
On 5 April 1993, Pope John Paul II appointed him cardinal bishop with the title of the Suburbicarian Church of Velletri-Segni. On 6 November 1998, he was elected Vice Dean of the College of Cardinals, and on 30 November 2002, the Holy Father approved the election as Dean of the College of Cardinals.
Ratzinger was one of John Paul II's closest associates and was elected pope on 19 April 2005.
Cardinal Joseph Ratzinger visited Croatia in 2001, as Prefect of the Sacred Congregation for the Doctrine of the Faith, attending a conference in Zagreb marking the 20th anniversary of the death of Cardinal Franjo Seper.
Ratzinger has written many books on theology, and some have been translated in Croatian, including: "Introduction to Christianity", "Salt of the Earth", "God and the World", "God Is Near Us", "Truth and Tolerance", "On the Way to Jesus Christ", "Jesus of Nazareth" and "The Spirit of the Liturgy".