The Alhambra Decree (also known as the Edict of Expulsion; Spanish: Decreto de la Alhambra, Edicto de Granada) was an edict issued on 31 March 1492, by the joint Catholic Monarchs of Spain (Isabella I of Castile and Ferdinand II of Aragon) ordering the expulsion of practising Jews from the Crowns of Castile and Aragon and its territories and possessions by 31 July of that year. The primary purpose was to eliminate the influence of practising Jews on Spain's large formerly-Jewish converso New Christian population, to ensure the latter and their descendants did not revert to Judaism. Over half of Spain's Jews had converted as a result of the religious persecution and pogroms which occurred in 1391. Due to continuing attacks, around 50,000 more had converted by 1415. A further number of those remaining chose to convert to avoid expulsion. As a result of the Alhambra decree and persecution in the years leading up to the expulsion, of Spain's estimated 300,000 Jewish origin population, a total of over 200,000 had converted to Catholicism to remain in Spain, and between 40,000 and 100,000 remained Jewish and suffered expulsion. An unknown number of the expelled eventually succumbed to the pressures of life in exile away from formerly-Jewish relatives and networks back in Spain, and so converted to Catholicism to be allowed to return in the years following expulsion.:17The edict was formally and symbolically revoked on 16 December 1968, following the Second Vatican Council. This was a full century after Jews had been openly practicing their religion in Spain and synagogues were once more legal places of worship under Spain's Laws of Religious Freedom.

In 1924, the regime of Primo de Rivera granted Spanish citizenship to a part of the Sephardic Jewish diaspora, though few people benefited from it in practice. In 2015, the government of Spain passed a law allowing dual citizenship to Jewish descendants who apply, to "compensate for shameful events in the country's past." Thus, Sephardi Jews who could prove that they are the descendants of those Jews expelled from Spain because of the Alhambra Decree would "become Spaniards without leaving home or giving up their present nationality." The Spanish law expired in 2019 and new applications for Spanish citizenship on the basis of Sephardic family heritage are no longer allowed. However, the descendants of the Jews exiled from the Iberian Peninsula may still apply for Portuguese citizenship.

The Second Ecumenical Council of the Vatican, commonly known as the Second Vatican Council, or Vatican II, was the 21st ecumenical council of the Roman Catholic Church.

The council met in St. Peter's Basilica in Rome for four periods (or sessions), each lasting between 8 and 12 weeks, in the autumn of each of the four years 1962 to 1965. Preparation for the council took three years, from the summer of 1959 to the autumn of 1962. The council was opened on 11 October 1962 by John XXIII (pope during the preparation and the first session), and was closed on 8 December 1965 by Paul VI (pope during the last three sessions, after the death of John XXIII on 3 June 1963).

Pope John XXIII called the council because he felt the Church needed “updating” (in Italian: aggiornamento). In order to connect with 20th-century people in an increasingly secularized world, some of the Church's practices needed to be improved, and its teaching needed to be presented in a way that would appear relevant and understandable to them. Many Council participants were sympathetic to this, while others saw little need for change and resisted efforts in that direction. But support for aggiornamento won out over resistance to change, and as a result the sixteen magisterial documents produced by the council proposed significant developments in doctrine and practice: an extensive reform of the liturgy, a renewed theology of the Church, of revelation and of the laity, a new approach to relations between the Church and the world, to ecumenism, to non-Christian religions and to religious freedom.

John W. O'Malley called this council "the most important religious event of the twentieth century".