Why does the pope wear white? Why do the cardinals wear red?

White is the color of the cassock worn by the Holy Father. This custom dates from the pontificate of Pope St. Pius V (1566-72), who was a Dominican priest and wanted to retain the color of his white religious habit.

Cardinals wear red as a sign of the blood of the martyrs: Pope Blessed John Paul II stated at an investiture of cardinals in 1998: “Red is a sign of the dignity of the office of a cardinal, signifying that you are ready to act with fortitude, even to the point of spilling your blood for the increase of the Christian faith.”