By Catholic News Service
Editor’s Note: The Message Staff contributed to this report.
VATICAN CITY (CNS) — When the Catholic Church celebrates World Mission Sunday for the 100th time in 2026, it will focus on the theme, “One in Christ, united in mission.”
The theme, chosen by Pope Leo XIV, is a reflection of his episcopal motto, “In Illo uno unum,” or literally “In the One, we are one.”
The Vatican announced the theme for the 2026 observance Oct. 31, 2025, which will be celebrated Oct. 18. The theme “highlights the unity of believers in the faith, founded on the unity of Christ with the Father, and the consequent shared mission of evangelization,” the Vatican said.
For World Mission Sunday, Catholics around the globe spend time learning about the Catholic missions, pray in support of missionaries and make donations to support the work of the church in mission lands.
The Pontifical Mission Societies USA website states: “World Mission Sunday is the Holy Father’s annual worldwide celebration of prayer, solidarity and support for the Church’s missionary life. Organized by the Society for the Propagation of the Faith, the oldest of the four Pontifical Mission Societies, it invites Catholics everywhere to participate in the Church’s global mission through prayer and financial support for mission dioceses most in need. The day reminds Catholics that the Church is missionary by nature. Mission is not limited to priests, religious sisters or missionaries serving abroad. Every baptized person shares responsibility for proclaiming the Gospel and supporting the growth of the Church throughout the world.”
Archbishop Fulton J. Sheen, who will be beatified Sept. 24 at The Dome at America’s Center in St. Louis, served as the national director of the Society for the Propagation of the Faith from 1950 to 1966.
World Mission Sunday is the Catholic Church’s “only canonically mandated second collection,” according to The Pontifical Mission Societies USA website, which states: “The Code of Canon Law specifically identifies support for the missions as a responsibility shared by the faithful throughout the world.”
In 2025, ahead of last year’s World Mission Sunday, Pope Leo issued a video explaining that “when I served as a missionary priest and then bishop in Peru, I saw first-hand how the faith, the prayer and the generosity shown on World Mission Sunday can transform entire communities.”
As an Augustinian priest, Pope Leo had served in the missions in Peru from 1985 to 1999 and then as apostolic administrator and later bishop of Chiclayo from 2014 to 2023.
Pope Pius XI instituted World Mission Sunday in 1926 to ensure that Catholics around the world shared responsibility for the missionary work of the church.
According to the United States Conference of Catholic Bishops, as the Church prepares to celebrate the 100th World Mission Sunday, “Pope Leo XIV calls us to unity in Christ, love and renewed missionary commitment ‘with joy and zeal in the Holy Spirit.’”
For more information on World Mission Sunday, visit https://pontificalmissions.org/wms-2026.