In the list of popes given in the Holy See's annual directory, Annuario Pontificio, the following note is attached to the name of Pope Leo VIII ( 963 – 965 ): At this point, as again in the mid-eleventh century, we come across elections in which problems of harmonising historical criteria and those of theology and canon law make it impossible to decide clearly which side possessed the legitimacy whose factual existence guarantees the unbroken lawful succession of the successors of Saint Peter.

Since Pope Leo XIII issued the bull Apostolicae Curae in 1896, the Catholic Church has insisted that Anglican orders are invalid because of changes in the Anglican ordination rites of the 16th century and divergence in understanding of the theology of priesthood, episcopacy and Eucharist.

Here he remained, commissioned by Pope Gregory XIII to lecture on polemical theology in the new Roman College.

* A manual of theology in 4 vols, Theologia eclectica, moralis et scholastica ( Augsburg, 1752 ; revised by Pope Benedict XIV for the 1753 edition published at Bologna )

Pope John Paul II repeatedly emphasized his respect for Eastern theology as an enrichment for the whole Church, declaring that, even after the painful division between the Christian East and the See of Rome, that theology has opened up profound thought-provoking prospectives of interest to the entire Church.

Born in Siena, a member of the illustrious banking family of Chigi and a great-nephew of Pope Paul V ( 1605 – 1621 ), he was privately tutored and eventually received doctorates of philosophy, law, and theology from the University of Siena.

Pope Pius XII developed an extensive theology of the family, taking issue with family roles, sharing of household duties, education of children, conflict resolution, financial dilemmas, psychological problems, illness, taking care of older generations, unemployment, marital holiness and virtue, common prayer, religious discussions and more.

Pope Innocent V was the author of several works of philosophy, theology, and canon law, including commentaries on the Pauline epistles and on the Sentences of Peter Lombard.

The new Pope issued a mandate ordering Bacon to write to him concerning the place of philosophy within theology.

Gutierrez also popularized the phrase " preferential option for the poor ", which became a slogan of liberation theology and later appeared in addresses of the Pope.

However, CELAM never supported liberation theology as such, since liberation theology was frowned upon by the Vatican, with Pope Paul VI trying to slow the movement after the Second Vatican Council.

He criticized radical liberation theology, saying, " this conception of Christ, as a political figure, a revolutionary, as the subversive of Nazareth, does not tally with the Church's catechisms "; however, he did speak of " the ever increasing wealth of the rich at the expense of the ever increasing poverty of the poor ", and affirmed that the principle of private property " must lead to a more just and equitable distribution of goods ... and, if the common good demands it, there is no need to hesitate at expropriation, itself, done in the right way "; on balance, the Pope offered neither praise nor condemnation.

In March 1983, Cardinal Ratzinger ( now Pope Benedict XVI ) head of the Vatican's Congregation for the Doctrine of the Faith ( CDF ), made ten observations of Gutiérrez's theology, accusing Gutiérrez of politically interpreting the Bible in supporting temporal messianism, and stating that the predominance of orthopraxis over orthodoxy in his thought proved a Marxist influence.

* BBC Religion and Ethics theological obituary of Pope John Paul II: his views on liberation theology

He opposed the political policies of Louis IV of Bavaria as Holy Roman Emperor, which prompted Louis to invade Italy and set up an antipope, Nicholas V. Pope John XXII faced controversy in theology involving his views on the Beatific Vision, and he opposed the Franciscan understanding of the poverty of Christ and his apostles.

He studied at the University of Paris and lectured there on theology until 1206, when Pope Innocent III, with whom he had formed a friendship at Paris, called him to Rome and made him cardinal-priest of San Crisogono.

In 1821 Pope Pius VII honoured Lingard with a triple doctorate-in theology, canon law and civil law-and a few years later Leo XII conferred upon him a gold medal generally only given to cardinals and princes.

Pope John Paul II wrote his theological dissertation on the mystical theology of Saint John of the Cross.

* Pope Benedict XVI, professor of theology at the University of Regensburg from 1969 to 1977, who retains the title, honorary professor ; he is not a former resident of the city of Regensburg, but his house, less than 1 kilometer from the city, lies in Pentling in the district of Regensburg.

In 1889, Pope Leo XIII authorized the founding of The Catholic University of America in Washington, D. C., and granted her Papal degrees in theology

However, Pope Urban V did not ratify the deed, specifically in relation to the department of theology, presumably due to pressure exerted by Charles IV, Holy Roman Emperor, who wished to avoid competition for the Charles University in Prague.

As a theology student in his hometown Sinigaglia, in 1814 he met Pope Pius VII, who had returned from French captivity.

The theology faculty of the University of Paris advised Charles not to make a hasty decision, but he recognised Clement as Pope in November and forbade any obedience to Urban.

Benedict XV supported the theology of Co-Redemptrix of the Virgin Mary

He also promoted Marian devotions in May in the spirit of Grignon de Montfort The dogmatic constitution on the Church issued by the Second Vatican Council quotes the Marian theology of Benedict XV.

The universal permission given to priests by Pope Benedict XVI in 2007 to celebrate the so-called " Tridentine " liturgy resulted in complaints from Jewish groups and some leaders in the Roman Catholic Church over what they perceived as being a return to a supersessionist theology.

Some branches of Liberation theology later were condemned by the Catholic Church's magisterium, especially by the Congregation of the Doctrine of Faith headed by then Cardinal Ratzinger ( the current Pope Benedict XVI ).

He was eventually ordained as a Dominican priest but then silenced for a year ( forbidden to teach theology ) by Cardinal Ratzinger ( now Pope Benedict XVI ) of the Holy See in 1988.

The dogma was affirmed repeatedly by the Roman Catholic Church and within Roman Catholic theology, e. g. at the Council of Lyon, 1274 ( Dz § 465 ); by Pope Benedict XII, 1341 ( Dz § 544 ); by Pope Clement VI, 1351 ( Dz § 574a ); at the Council of Constance, 1418 ( Dz § 583 ); at the Council of Florence, 1439 ( Dz § 698 ); by Pope Julius III at the Council of Trent, 1551 ( Dz § 874 ); by Pope Benedict XIV, 1743 ( Dz § 1469 ); by Pope Pius VI, 1794 ( Dz § 1529 ); and by Pope Leo XIII, 1887 ( Dz § 1919 ), inter alia.

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From his early years, the Eucharist had a central place in the theology of Joseph Ratzinger and in his role as Pope Benedict XVI as well as in his book God Is Near Us: The Eucharist, the Heart of Life he strongly encouraged Eucharistic adoration.

It is widely believed that the conservatism of Pope Benedict XVI stems from his reaction to student protests at the University of Tübingen in 1968, when he served as a professor of theology.

In 1986, the Vatican declared that although a tenured professor, Curran could no longer teach theology at Catholic University of America schools, because " clashes with Church authorities finally culminated in a decision by the Sacred Congregation for the Doctrine of the Faith, headed by then-Cardinal Joseph Ratzinger Pope Benedict XVI, that Curran was neither suitable nor eligible to be a professor of Catholic theology.

Its most famous academic, the current Pope Benedict XVI, served as a professor there until 1977 and formally retains his chair in theology.

* Pope Benedict XVI, faculty member, theology, 1969 – 1977

Nevertheless, official theological statements such encyclical letters constitute part of the theology of Pope Benedict XVI.

In absence of a large body of papal teachings of Benedict XVI, the Ratzinger theology is often cited.

While there are likely to be many similarities between the teachings of Benedict and Ratzinger, the theology of Joseph Cardinal Ratzinger has been somewhat unique because of his " watchdog " office, which required him to address a larger variety of issues.

In his theology of covenant, Benedict provides a unified interpretation of Scripture centered on the person and work of Jesus, with implications ranging from the Eucharist to the proper understanding of ecumenism.

Benedict holds that Christology must be rooted the covenantal theology of the New Testament, which is grounded in the unity of the entire Bible.

Pope John Paul II and Benedict have strongly opposed liberation theology as a political movement.

Benedict, in his most recent book, indicated that evolution, although more than a theory, was still not and as a scientific theory could not be definitively proven and that in any case, the creation and evolution of the universe and its matter could not comprehensively be explained by empirical, existential, logical methods of science – necessitating other disciplines like philosophy and theology to fill in where science could not be wholly applied or where questions were not solveable by, or in the realm of, the sciences.