Pope Pius XI (1922-1939). It was this pope who established World Mission Day in 1926, in response to a request from the Society for the Propagation of the Faith. The very first worldwide celebration was held in 1927. The day is meant to unite Catholics across the globe to respond to their baptismal calling to spread the Gospel and support those communities where the Church is young, materially poor, lacking vocations, or even persecuted.
In his encyclical Rerum Ecclesiae (1926), widely considered the Magna Carta of Catholic mission, Pius XI urged bishops worldwide to foster local vocations, promoting an indigenous clergy and religious rather than relying on foreign missionaries. This task would involve establishing local seminaries and houses of formation, all of which would contribute to planting the Church permanently among local peoples and within their cultures. A second encyclical by Pius XI, Rerum Orientalium, focused on the promotion of missionary activity in the Eastern Catholic Rites.
Pope Pius XII (1939-1958). This papacy occurred during the extremely difficult period of World War II (1939-1945). Probably the most problematic challenge was dealing with Hitler and the persecution of the Jewish people. Untold obstacles had to be addressed as the Church sought to remain faithful to her mission. During his papacy, Pius XII issued two mission encyclicals: Evangelii Praecones (1951) and Fidei Donum (1957); each one captures many themes from his World Mission Day messages.
Evangelii Praecones (Promoting Catholic Missions) was issued on the twenty-fifth anniversary of Pius XI’s Rerum Ecclesiae. Despite the interruptions of the Second World War, missionary endeavors achieved a great deal, as noted in the encyclical, especially in the growth of indigenous clergy, religious, and bishops. Missionaries were encouraged to build upon the good elements of local cultures: customs, local feasts, native witnesses and martyrs, and local arts. Fidei Donum placed special emphasis on the Church in Africa, especially as many countries there were becoming independent. The goal of the mission was slowly but surely being achieved: the establishment “firmly and permanently” of the local Church.
Pope Saint John XXIII (1958-1963). During his short pontificate of less than five years, John XXIII issued eight encyclicals on topics including global peace, social justice, human dignity, and Church unity. He was known as “good Pope John” and is most remembered for convening the Second Vatican Council, which brought significant changes to the Church and her mission. He only presided over the first session of the Council in 1962.
The specific mission encyclical from John XXIII was titled Princeps Pastorum (1959). Key emphases of this document centered on the promotion of a native local clergy, the need for self-reliance in local churches, respect for local cultures, and encouragement of lay persons to actively engage in the social mission of the Church. Two other documents of John XXIII had deep missionary ramifications: [1] Mater et Magistra (1961) (Christianity and Social Progress) spoke of addressing economic imbalances, poverty, and the relationship between wealthy and developing nations; [2] Pacem in Terris (1963) (Peace on Earth) focused on human rights, world peace, and international cooperation in the wake of the cold war and the Cuban missile crisis.
Pope Saint Paul VI (1963-1978). Paul VI made a remarkable contribution to the Vatican Council by guiding three sessions (1963-1965) and bringing the Council to a successful conclusion. Several Council documents contributed to a profound renewal of missionary activity; they are Lumen Gentium (Church), Gaudium et Spes (Church in the Modern World), Unitatis Redintegratio (Ecumenism), Ad Gentes (Mission), Apostolicam Actuositatem (Laity), and Nostra Aetate (Non-Christian Religions).
Undoubtedly, the greatest mission contribution of Paul VI was his 1975 apostolic exhortation, Evangelii Nuntiandi (Evangelization in the Modern World); this inspiring document renewed the Church’s missionary focus and cemented the principle that the Church exists to evangelize. The document affirms “evangelizing all people constitutes the essential mission of the Church” and that evangelizing is “the grace and vocation proper to the Church” (EN, 14). “For the Church, evangelizing means bringing the Good News into all strata of humanity” (EN, 18).
Paul VI was the first pope to proclaim the World Mission Day Message on the radio (October 19, 1963, Saturday before Mission Sunday). His Mission Day messages called for unity, peace, and the evangelization of the modern world. Paul VI clearly deserves the accolade: Modern Missionary Pope!
Pope John Paul I (1978). Serving only for 33 days, John Paul I was the only pope in modern history who did not issue an annual World Mission Day message. He surprised everyone by choosing two names for his official title; his purpose was to indicate that he intended to continue the renewal fostered by Vatican II, which was guided by Popes John XXIII and Paul VI. His affability, humility, and contagious joy earned him the popular moniker, “the smiling pope.”
Pope Saint John Paul II (1978-2005). Continuing the use of a double name, this pontiff served for over 26 years, making him the third longest-serving pope in Church history. He was the first non-Italian pope in 455 years. He continued the practice of foreign trips initiated by Paul VI, who had made nine major international journeys and was the first pope to fly on an airplane.
During his pontificate, John Paul II issued over two dozen messages for World Mission Day. He consistently emphasized that evangelization is a fundamental duty for all Christians; he urged the faithful to support missionary efforts through a variety of initiatives, including prayer, personal engagement, respect for human dignity, and youth involvement. Particularly in the 1990s, his messages spoke of a “new evangelization,” designed to reawaken faith and involvement in traditionally Christian areas. His documents included fourteen encyclicals, fifteen apostolic exhortations, and numerous other writings. His 1990 mission encyclical Redemptoris Missio (On the Permanent Validity of the Church’s Missionary Mandate) presents a comprehensive overview of contemporary evangelization; he starkly proclaims that “Mission is an issue of faith” (RM 11), for without faith no mission is possible!
Pope Benedict XVI (2005-2013). In modern Church history, Benedict is the first pope to resign; he died in 2022. During his pontificate, he issued seven World Mission Day messages, striving to show the interconnected themes of Christian charity, Gospel proclamation, global ecclesial communion, and involvement of the laity. He did not write an encyclical specifically dedicated to the Church’s missionary activity. Also, in contrast to his predecessor, Benedict engaged in few international journeys.
Pope Francis (2013-2025). Francis is the first pope to take the name Francis, the first pope from the Americas, and the first Jesuit pope. He issued fourteen annual messages for World Mission Day from 2013 to 2026, exploring a variety of themes: having a missionary heart, witnessing to mercy, engaging young people, dynamic witnessing, having hearts on fire with feet on the move, being heralds of hope, and living personal unity with Christ.
Undoubtedly, it was Francis’ 2013 apostolic exhortation, Evangelii Gaudium (The Joy of the Gospel), that eloquently articulated his profound insights into mission. He asserted that “missionary outreach is paradigmatic for all the Church’s activity” (n.15). “Throughout the world, let us be ‘permanently in a state of mission’” (n.25). The Church must attempt “to put all things in a missionary key” (n.34). All Christians must endeavor to become “missionary disciples” (n.40, 50, 119-121, 173). One could validly assert that Evangelii Gaudium is the contemporary bible of missionary evangelization!
Pope Leo XIV (2025-). Leo’s first message for World Mission Day on October 18, 2026, marks the one hundredth anniversary of this event; the theme of the message is: “One in Christ, United in Mission.” Leo emphasizes that no baptized person is exempt from engagement in the Church’s mission; he highlights the need for reconciled communities and peaceful hearts to radiate Christ’s message in a conflicted world. Leo also asserts that union with Christ lies at the heart of mission. Clearly, Leo’s insights reflect his life experience as a missionary priest and bishop in Peru.
A missionary spirit also emerges from Leo’s first encyclical, Magnifica Humanitas (Magnificent Humanity). It elaborates on Catholic social teaching on topics such as the common good, solidarity, subsidiarity, and social justice. The document notes the limitations of artificial intelligence (AI), as it lacks consciousness, empathy, and moral judgment. This groundbreaking document will certainly bear much fruit in the future!
It is the author’s dream that this brief presentation will serve as an “appetizer” to delve more deeply into the Church’s profound mission theology and practice as they have evolved over the past century. You will encounter a grand “missionary banquet”!
James H. Kroeger, MM, served mission in Asia (Philippines and Bangladesh) for over five decades; recently he authored Walking with Pope Francis (Paulines, Manila) and A Joyful Journey with Pope Francis and Living in Joyful Hope (Claretians, Manila).
