VATICAN CITY — When the Catholic Church celebrates World Mission Sunday for the 100th time in 2026, it will focus on 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 Oct. 31 the theme for the 2026 observance, which will be celebrated Oct. 18. A papal message on the theme is expected in early February.
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.
Ahead of the 2025 celebration, Pope Leo had 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.
