Further back in history, other popes took actions that have moved theological and pastoral discussion forward.
"Pius XI comes to mind with his refusal of the ‘prisoner of the Vatican' mentality of previous popes who rejected the formation of the Italian state," Avella said.
Pius XI (1857-1939) was indeed responsible for one of the most important events in the history of the Vatican on Feb. 11, 1929 -- the signing of the Lateran Treaty between the pope and King Emmanuel III of Italy. The agreement ended almost 60 years of papal isolation, when the popes even refused to appear at the balcony on Saint Peter's Square, allowing the Vatican and Italy to recognize each other as sovereign nations.
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Other popes, such as Leo XIII (1810–1903), reset the parameters of discussion on such issues as economic justice. In his 1891 revolutionary Rerum novarum, the first major encyclical on capitalism and social issues, Leo XIIII defended private property, as well as the rights of workers to form associations for better treatment.
Pope John XXIII (1881-1963), who soon will be made saint along with John Paul II, recommended putting aside doctrinal issues and focusing on the modern world's trends when he opened the Second Vatican Council on Oct. 11, 1962.
"As Father John O'Malley S.J. noticed, John XIII's remarks gave a tenor and direction to Vatican II that was not expected at the time," Avella said. "It was free of anathemas, it had a more conciliatory and dialogical tone than previous councils and broke new ground in such topics as relations with the Jews, religious liberty and the role of the church in the modern world."
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But liberal and conservative are relative terms in the Catholic Church, after all.
According to Thomas F. X. Noble, professor of history at Notre Dame and an expert on the history of the papacy, the concept also applies to Pope Francis, whose directness and humble style continue to win the hearts of millions.
"On questions of economic justice, Francis is, in secular terms, radical," Noble told Discovery News. "He says we need a deeper theology for understanding women. But he says the door is closed to the ordination, so where this goes will be revealed in time."
As for Francis's comment on gays, Noble found it "a remarkable pastoral statement."
"Yet we have no policy. Is this conservative? Traditional? Simply Catholic? I think we are in for some surprises in the next year or two. In the end, Francis will baffle the commentariat the way John Paul II did," Noble said.