The Feast Day of Saint Robert Bellarmine is observed in Vatican City every September 17. This day is significant as it coincides with the name day of the incumbent pope, currently Pope Leo XVI, who was born Robert Francis Prevost. The celebration honors Saint Robert Bellarmine, a notable figure in the Catholic Church, who was born on October 4, 1542, and became a cardinal and Doctor of the Church. He is recognized for his contributions to theology, particularly through his work "Disputationes de Controversiis," which defends Catholic doctrine. The feast day became a public holiday in the Vatican following Pope Leo XIV's election in May 2025, replacing the previous holiday for Pope Francis. The day is marked by religious observances and reflects the longstanding tradition of celebrating the name day of the reigning pope.