7 Papal Encyclicals That Changed the World

They are somewhere in length between a newspaper column and a book. But papal encyclicals wield an outsize influence. Papal encyclicals have inspired revolutions, changed cultures, and helped topple ideologies and empires. Sometimes they meet with universal acclaim. Some arouse widespread disdain and dissent. Either way, when a pope issues his thoughts on an important matter of faith and morals, the world listens—even if it doesn’t always agree.

There are some encyclicals, in particular, that have left, it seems, an indelible impact on the world—whether the world of Catholicism, the broader Christian community, or beyond. Here are seven encyclicals that have changed the world, in one fashion or another, listed in chronological order:

Rerum Novarum, Leo XIII 1891: This encyclical is the foundation of all modern Catholic social teaching. Rerum Novarum sought a Christian basis for property rights in the fact that man is created in the image of God. But it also called out greedy industrialists for abusing workers and affirmed the right of the state to intervene on their behalf. At a time of great social upheaval, the encyclical thus sketched out a uniquely Catholic response to the challenges of worker rights, urbanization, industrialization—avoiding the extremes of both socialism and laissez faire capitalism. This inspired a movement known as distributism, so named because its adherents believe property ownership should be widely distributed, instead of concentrated in the hands of wealthy robber barons or socialist bureaucrats. Notable distributists include G.K. Chesterton and Hilaire Belloc. Rerum Novarum has inspired other encyclicals too, most notably Quadragesimo Anno, itself an indispensable pillar of Catholic social teaching. Distributist themes are even reflected in one of the most all-time popular Christian works of fiction: The Lord of the Rings.

Providentissimus Deus, Leo XIII 1893: There had been other encyclicals on the Bible before, but none as momentous as this, and probably none since. Providentissimus Deus drew a battle line against modernism: Leo XIII declared that it is inconsistent to say that the Bible has errors and was still divinely inspired. Without taking an anti-scientific stance, the pope affirmed an uncompromising doctrine of inerrancy against those who claimed the Bible is only without error in narrow matters of faith and morals. Catholic biblical theology has never been the same since. As one scholar has put it, the encyclical is “the magna carta of modern Catholic biblical studies.” Now this may seem like an arcane matter best left to scholars, but it’s one that affects all of us. Pope Leo XIII worried that a weak doctrine of inerrancy would diminish reverence for Scripture among all Catholics, causing them to stop believing it in entirely. In this warning are the seeds of the later emphasis on Bible reading among lay Catholics. Leo XIII himself expressed a “desire that this grand source of Catholic revelation should be made safely and abundantly accessible to the flock of Jesus Christ.”

Pascendi Dominici Gregis, Pius X 1907: In this encyclical, the Catholic Church declared war on modernism. Pius X issued a wholesale condemnation of the cultural trend, particularly its tendencies towards individualism, agnosticism, and relativism. The confrontational tone of the encyclical has made it unpopular in certain quarters inside and outside the Church, but Pius X should be credited for taking a stand as the world was headed over the cliff. To paraphrase the mission statement of a certain publication, under Pius X, the Church stood athwart history, yelling ‘stop,’ when few were inclined to do so, or listen to those who did. His refusal to make peace with a confused and disturbed world left its definitive mark on Catholic culture for at least the next sixty years. Some might say that the spirit of St. Pius X lives on today and can be seen perhaps mostly recently in Pope Benedict XVI’s denunciation of the ‘dictatorship of relativism.’

Casti Connubii, Pius XI 1930: Evangelium Vitae gets all the credit, but this is the encyclical that really established (or reaffirmed, rather) the Catholic teaching on contraception. At one time, artificial contraception was universally viewed as sinful among Christians. But, at the 1930 Lambeth conference, the Anglican church reversed its position, prompting Pius XI to issue Casti Connubii, making it clear that the Catholic Church was not about to follow suit, even as many other Protestant denominations did. The Church’s teaching on contraception is almost unique to Catholicism today. It is one way the Church upholds a truly consistent ethic of life, which is why it is not surprising that Casti Connubii also took firm stands against abortion and eugenics.

Pacem in Terris, John XXIII 1963: Issued months after the Cuban missile crisis, Pacem in Terris sounded an urgent call for peace, based on a broad Christian vision of divine order, human rights, and the common good. Pacem in Terris had an immediate impact: the New York Times printed the full text and President John F. Kennedy praised it. It’s also left a lasting impression: every encyclical dealing with social issues since then has cited it and Pope Benedict XVI called it an “immortal encyclical” in a 2006 address, according to the Catholic World Report. “Pacem in Terris inserted the Catholic Church firmly into the late-20th century debate on human rights, which proved to be such an important tool in the hands of those who eventually brought down the Berlin wall and thus made an enormous contribution to peace,” Catholic writer George Weigel told the Catholic World Report.

Humanae Vitae, Paul VI 1968: Humanae Vitae threw down the gauntlet on the issue of contraception, making it one of the most controversial and disliked encyclicals of all time. Humanae Vitae boldly laid out the Church’s teaching against artificial contraception—right as the West was in the midst of the sexual revolution and after a commission of theologians had recommended changing the teaching. The Church’s continued stance on this issue remains a cornerstone of faith to some, and a stumbling block to others. But more than forty years afterwards, with soaring divorce rates and plummeting birthrates in much of the Western world, it’s hard to not to see Paul VI as a prophetic voice on the evils of the contraceptive mentality.

Redemptor Hominis, John Paul II 1979: His first encyclical, Redemptor Hominis laid out John Paul II’s agenda for the rest of his papacy. In particular, it set the stage for his confrontation with communism, rooted in John Paul II’s emphasis on the dignity of the human person and his personal encounter with Christ. “In the face of the prospect of Communist collectivism, he made a personalist affirmation. It was like a time bomb: The words Marxism and Communism are not found in Redemptor Hominis. But it is on the foundations, on the idea that one has of the human person, that the Pope placed the confrontation,” Cardinal Georges Cottier told ZENIT in 2004. A few months after the encyclical, John Paul II led a nine-day pilgrimage through Poland, in which one third of the population—thirteen million people—attended at least one of his events. The pilgrimage is credited with fueling the anti-communist Solidarity movement in Poland, one of the first dominoes to fall in the eventual collapse of communism.

Honorable Mentions

These encyclicals did not have a world-altering impact (at least in the opinion of this author), but are nonetheless immensely important:

Aeterni Patris, Leo XIII 1879: This encyclical is credited with helping to revive Thomism in the Church. Today, one could argue that Aquinas is the single most important Catholic theologian and philosopher, apart from the apostles and the New Testament writers. As Leo XIII himself wrote, quoting one of Aquinas’ commentators, “Among the Scholastic Doctors, the chief and master of all towers [is] Thomas Aquinas, who, as Cajetan observes, because ‘he most venerated the ancient doctors of the Church, in a certain way seems to have inherited the intellect of all.’”

Quas Primas, Pius XI 1925: This encyclical established the Feast of Christ the King, a reminder of the importance of Christ’s kingship on this earth. ‘Christ the King’ became the rallying call of those fighting for the Church in the Cristero War in Mexico.

Veritatis Splendor, John Paul II 1993: Viewed by some as his most important encyclical, Veritatis Splendor was the “first papal encyclical in history on the foundations of moral theology,” according to the Catholic News Service.

Evangelium Vitae, John Paul II 1995: Another leading candidate for his most important encyclical, Evangelium Vitae issues a strong call for a culture of life and reaffirms the Catholic teaching on abortion, euthanasia, and contraception. It also broke important new ground on the Church’s position on the death penalty in the context of its broader commitment to a culture of life.

Fides et Ratio, John Paul II 1998: This is must-reading for anyone who seeks to understand how faith and reason are related. Such a question is one that touches upon so many diverse aspects of our faith—apologetics, the role of science, the relationship between natural law and the moral teachings of the Church, not to mention how we understand our own journey towards faith in God.


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Stephen Beale is a freelance writer based in Providence, Rhode Island. Raised as an evangelical Protestant, he is a convert to Catholicism. He is a former news editor at GoLocalProv.com and was a correspondent for the New Hampshire Union Leader, where he covered the 2008 presidential primary. He has appeared on Fox News, C-SPAN and the Today Show and his writing has been published in the Washington Times, Providence Journal, the National Catholic Register and on MSNBC.com and ABCNews.com. A native of Topsfield, Massachusetts, he graduated from Brown University in 2004 with a degree in classics and history. His areas of interest include Eastern Christianity, Marian and Eucharistic theology, medieval history, and the saints. He welcomes tips, suggestions, and any other feedback at bealenews at gmail dot com. Follow him on Twitter at https://twitter.com/StephenBeale1

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